_Ellipsostylus_.) In the figured variety (Pl. 14, fig. 7) the ends of the
surface spines are connected by a very delicate network, so as to form an
outer veil. This may further be separated as a peculiar genus
_Ellipsoxiphium palliatum_.

_Dimensions._--Longer axis 0.08 to 0.13, shorter axis 0.06 to 0.11; pores
and bars 0.008; length of the polar spines 0.06 to 0.12, basal breadth
0.01.

_Habitat._--Pacific, central area, Stations 270 to 274, from 2350 to 2925
fathoms.

2. _Ellipsoxiphus flosculus_, n. sp.

Proportion of the major axis to the minor = 6 : 5. Shell very thick walled,
with regular, hexagonal meshes, eight to nine on the half equator, three to
four times as broad as the bars. The inner contour of the meshes is
circular, the outer six-lobed (similar to _Xiphostylus phasianus_, Pl. 13,
fig. 9). Polar spines three-sided pyramidal, about as long as the major
axis of the shell; their basal thickness equals one mesh.

_Dimensions._--Longer axis 0.12, shorter axis 0.1; pores 0.012 to 0.015,
bars 0.004; length of the polar spines 0.12 to 0.15, basal breadth 0.015.

_Habitat._--Fossil in the Tertiary rocks of Barbados (Teuscher).

3. _Ellipsoxiphus fragilis_, n. sp.

Proportion of the major axis to the minor = 4 : 3. Shell thin walled, with
regular, circular meshes, twice as broad as the bars; ten to twelve on the
half equator. Surface smooth. Polar spines cylindrical, at the apex
conical, half as long as the major axis.

_Dimensions._--Longer axis 0.16, shorter axis 0.12; pores 0.008, bars
0.004; length of the polar spines 0.09, basal breadth 0.008.

_Habitat._--South Atlantic, Station 325, surface.

Subgenus 2. _Ellipsoxiphilla_, Haeckel.

_Definition._--Network of the shell irregular, with pores of different size
or form.

{297}4. _Ellipsoxiphus claviger_, n. sp. (Pl. 14, fig. 3).

  _Xiphosphæra clavigera_, Haeckel, 1881, Prodromus et Atlas.

Proportion of the major axis to the minor = 5 : 4. Shell thick walled, with
irregular network; meshes roundish or circular, double contoured, of
unequal size, twice to four times as broad as the bars; eight to ten on the
half equator. Polar spines club-shaped, with prominent edges, about as long
as the minor axis; thicker in their middle part than at both ends (differs
from _Xiphosphæra clavigera_ by the ellipsoidal form of the shell, and the
double length of the spines).

_Dimensions._--Longer axis 0.15. shorter axis 0.12; pores 0.007 to 0.015,
bars 0.004; length of the polar spines 0.12, thickness in the middle part
0.02.

_Habitat._--Central area of the Pacific, Station 272, depth 2600 fathoms.

5. _Ellipsoxiphus suessi_, Dunikowski.

  _Ellipsoxiphus suessi_, Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss.
  Wien, Bd. xlv. p. 26, Taf. v. fig. 50.

Proportion of the major axis to the minor = 7 : 5. Shell thick walled, with
irregular, roundish meshes, six to eight on the half equator, twice to
three times as broad as the bars. Polar spines nearly cylindrical, blunt,
as long as the major axis.

_Dimensions._--Longer axis 0.14; shorter axis 0.1; pores 0.018 to 0.023,
bars 0.01; length of the polar spines 0.12; thickness of them 0.035.

_Habitat._--Fossil in the Alpine Lias, Schafberg near Salzburg, Dunikowski.

6. _Ellipsoxiphus parvoforaminus_, Dunikowski.

  _Ellipsoxiphus parvoforaminus_, Dunikowski, 1882, Denkschr. d. k. Akad.
  d. Wiss. Wien, Bd. xlv. p. 26, Taf. v. fig. 51.

Proportion of the major axis to the minor = 7 : 6.  Shell thick walled,
with irregular, roundish or oval meshes, ten to twelve on the half equator,
scarcely as broad as the bars.  Polar spines conical, shorter than the
minor axis.

_Dimensions._--Longer axis 0.14, shorter axis 0.12; pores 0.016 to 0.01,
bars 0.01 to 0.02; length of the polar spines 0.1, basal thickness 0.045.

_Habitat._--Fossil in the Alpine Lias, Schafberg near Salzburg, Dunikowski.

7. _Ellipsoxiphus bipolaris_, n. sp. (Pl. 14, fig. 11).

  _Xiphosphæra bipolaris_, 1881, Prodromus et Atlas.

Proportion of the  major axis to the minor = 8 : 7.  Shell thick walled,
with irregular, roundish meshes, twice to three times as broad as the bars;
sixteen to twenty on the half equator. Polar spines short and thick,
three-sided pyramidal, scarcely half as long as the shorter radius of the
shell; surrounding the base of every spine is a circle of eight to nine
shorter spines.

_Dimensions._--Longer axis 0.08, shorter axis 0.07; pores 0.003 to 0.007,
bars 0.002; length of the polar spines 0.02 to 0.03, basal thickness 0.02.

_Habitat._--Tropical part of the Western Pacific, Station 225, depth 4475
fathoms.

{298}8. _Ellipsoxiphus atractus_, n. sp. (Pl. 14, fig. 1).

Proportion of the major axis to the minor = 3 : 2. Shell spindle-shaped,
very thick walled, with roundish, very irregular meshes, twice to five
times as broad as the bars; eight to twelve on the half equator. The meshes
are partly simple, oblong, partly lobed or composed of two to four
(commonly three) confluent meshes. Surface smooth. Polar spines very short
and thick, shorter than the minor radius of the shell, three-sided
pyramidal, with prominent, somewhat contorted edges.

_Dimensions._--Longer axis 0.15, shorter axis 0.1; meshes 0.007 to 0.02,
bars 0.004; length of the polar spines 0.04, basal thickness 0.03.

_Habitat._--Central area of the Pacific, Station 268, depth 2900 fathoms.

Genus 126. _Axoprunum_,[165] n. gen.

_Definition._--#Ellipsida# with simple ellipsoidal shell, the main axis of
which is prolonged at both poles into two opposite spines of equal size and
similar form. Within the cavity of the shell four radial rods arise from
its inner surface, two in the main axis, two in the smallest axis,
perpendicular to the former; their free inner ends are at the same distance
from the centre.

The genus _Axoprunum_ possesses precisely the same shell as the foregoing
_Ellipsoxiphus_, but differs from it in a very remarkable peculiarity. The
two polar spines are centripetally prolonged into two internal beams, and
perpendicular to these are two other, opposite, transverse beams, marking
the minor axis of the ellipsoid. The free inner ends of all four radial
rods bear little thickened knobs, and are at the same distance from the
centre. It therefore appears as though a central, spherical, medullary
shell had been lost, and this gives a strong support to the important
hypothesis, that in many #Sphærellaria#, where the medullary shell is
absent, it may have been lost by phylogenetic reduction or retrograde
metamorphosis. In this case _Axoprunum_ (and _Ellipsoxiphus_) would arise
from _Lithatractus_.

1. _Axoprunum stauraxonium_, n. sp. (Pl. 48, fig. 4).

Shell ellipsoidal, one and one-third times as long as broad, with smooth
surface. Network regular, with circular meshes four times as broad as the
bars. Two polar spines three-sided pyramidal, half as long as the shell, as
thick at the base as a single mesh. Four inner radial beams (lying, two in
the major and two in the minor axis of the ellipsoid) very thin, at the
central free ends knob-like, thickened. The distance between two opposite
beams equals one-third of the minor axis, and indicates probably the
diameter of the lost spherical medullary shell. (Three perfect and complete
specimens of the same size and shape were observed.)

{299}_Dimensions._--Major axis of the ellipsoid 0.14, minor axis 0.11;
pores 0.012, bars 0.003; length of the polar spines 0.07, basal breadth
0.012. (Diameter of the lost medullary shell 0.03?)

_Habitat._--South Atlantic, Station 338, depth 1990 fathoms.

Genus 127. _Ellipsostylus_,[166] n. gen.

_Definition._--#Ellipsida# with simple ellipsoidal shell, the main axis of
which is prolonged at both poles into two opposite spines of different size
or form.

The genus _Ellipsostylus_ differs from _Ellipsoxiphus_ only in the unequal
size or different form of the polar spines, which in the former are equal.
This difference does not seem important at first, but in the further
development it produces very singular and strange forms. Theoretically it
is always important, because the fundamental haplopolar form of the monaxon
body becomes diplopolar by this differentiation.

Subgenus 1. _Ellipsostyletta_, Haeckel.

_Definition._--Network of the shell regular, with pores of equal size and
similar form.

1. _Ellipsostylus ornithoides_, n. sp.

Proportion of the major axis of the ellipsoid to the minor = 4 : 3. Shell
thin walled, with regular, circular meshes and hexagonal framework between
them, like that of _Xiphostylus favosus_ (Pl. 13, fig. 4). Circular pores
about as broad as the bars; eight to nine on the half equator. Surface
smooth. Polar spines three-sided pyramidal, as broad at the base as a
single hexagon; the longer spine as long as the major axis, the shorter
half as long.

_Dimensions._--Longer axis of the ellipsoidal shell 0.16, shorter axis
0.12; pores and bars 0.006; length of the longer polar spine 0.16, of the
shorter 0.08.

_Habitat._--North Pacific, Station 241, depth 2300 fathoms.

2. _Ellipsostylus avicularis_, n. sp.

Proportion of the major axis to the minor = 3 : 2. Shell thick walled, with
regular, rosette-shaped meshes, three times as broad as the bars; ten to
twelve on the half equator. Every mesh on the outer margin with five to six
rounded lobes, as in _Xiphostylus phasianus_ (Pl. 13, fig. 9). Surface
smooth. Polar spines sharp edged, thick; the longer straight and equal to
the longer axis, the shorter half as long, shaped like a bird's head.

_Dimensions._--Longer axis 0.18, shorter axis 0.12; pores 0.015, bars
0.005.

_Habitat._--South Pacific, Station 300, depth 1375 fathoms.

{300}3. _Ellipsostylus psittacus_, n. sp. (Pl. 13, fig. 6).

Proportion of the major axis to the minor = 4 : 3. Shell thin walled, with
regular or subregular rosette-shaped meshes, twice as broad as the bars;
eight to nine on the half equator; each mesh with three to four rounded
lobes. Surface smooth. Polar spines sharp edged, very unequal; longer spine
about twice as long as the major axis, somewhat curved; shorter spine
scarcely longer than the radius, shaped like a bird's head.

_Dimensions._--Longer axis 0.08, shorter axis 0.06; pores 0.01, bars 0.005;
length of the polar spines--longer 0.15, shorter 0.05.

_Habitat._--Central area of the Pacific, Station 266, depth 2750 fathoms.

4. _Ellipsostylus aquila_, n. sp. (Pl. 13, fig. 1).

Proportion of the major axis to the minor = 7 : 6. Shell thick walled, with
subregular, circular meshes, five to six times as broad as the bars; ten to
twelve on the half equator. Surface smooth. Polar spines sharp edged
(six-sided?), very unequal; longer spine straight, about equal to the minor
axis; shorter spine obliquely inserted, scarcely half as long, shaped like
a bird's head.

_Dimensions._--Longer axis 0.15, shorter axis 0.13; pores 0.02, bars 0.004;
length of the polar spines--longer 0.1, shorter 0.05.

_Habitat._--Central area of the Pacific, Station 272, depth 2600 fathoms.

5. _Ellipsostylus columba_, n. sp. (Pl. 13, fig. 3).

Proportion of the major axis to the minor = 4 : 3. Shell egg-shaped, thin
walled, with regular, circular meshes, three times as broad as the bars;
ten to twelve on the half equator. Surface somewhat thorny. Polar spines
nearly of equal length (equal to the major axis), but of very different
form; one straight, pyramidal, and obliquely inserted, the other like a
bird's head.

_Dimensions._--Longer axis 0.08, shorter 0.06; pores 0.003, bars 0.01;
length of the spines 0.09.

_Habitat._--South Atlantic, Station 332, surface.

6. _Ellipsostylus ciconia_, n. sp. (Pl. 13, fig. 8).

Proportion of the major axis to the minor = 7 : 5. Shell egg-shaped, thick
walled; the meshes very small, regular, circular, three times as broad as
the bars; sixteen to twenty on the half equator. Surface uneven. Polar
spines nearly cylindrical, pointed; the smaller obliquely inserted, equal
to the major axis; the larger more than twice as long and thick, furrowed
at its base. (Compare with this and the allied species _Rhabdolithis pipa_,
Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. i. fig. 27.)

_Dimensions._--Longer axis 0.07, shorter 0.05; pores 0.003, bars 0.001;
length of the polar spines--longer 0.2, shorter 0.08.

_Habitat._--North Pacific, Station 253, depth 3125 fathoms.

{301}Subgenus 2. _Ellipsostylissa_, Haeckel.

_Definition._--Network of the shell irregular, with pores of different size
or form.

7. _Ellipsostylus megadictya_, Haeckel.

  _Stylosphæra megadictya_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 299, Taf. viii. fig. 13.

Proportion of the major axis to the minor = 5 : 4. Shell thin walled, with
irregular, roundish, large meshes, four to five times as broad as the bars;
only four to five on the half equator. Surface smooth. Polar spines
straight, thin, angular; the shorter equal to the minor axis, the longer
four times as large.

_Dimensions._--Longer axis 0.05, shorter axis 0.04; meshes 0.01, bars
0.002; length of the polar spines--longer 0.12, shorter 0.03.

_Habitat._--Philippine Sea, 3300 fathoms, Ehrenberg.

8. _Ellipsostylus gallinula_, n. sp.

Proportion of the major axis to the minor = 3 : 2. Shell thick walled, with
irregular, roundish meshes, twice to four times as broad as the bars; eight
to ten on the half equator. Surface thorny. Polar spines conical, straight;
the longer twice as long as the major axis, the minor scarcely half as
long.

_Dimensions._--Longer axis 0.15, shorter 0.12; pores 0.01 to 0.02, bars
0.002 to 0.004.

_Habitat._--North Pacific, Station 253, surface.

9. _Ellipsostylus hirundo_, n. sp. (Pl. 13, fig. 2).

Proportion of the major axis to the minor = 4 : 3. Shell thick walled, with
irregular, roundish meshes, three to five times as broad as the bars; eight
to ten on the half equator. The inner aperture of every mesh is fenestrated
by a delicate lamella of silex, perforated by six to eight very small
circular pores. Polar spines sharp edged, more or less curved, the shorter
equal to the minor axis, the longer twice as long.

_Dimensions._--Longer axis 0.16, shorter 0.12; pores 0.01 to 0.02, bars
0.003 to 0.006; length of the polar spines--longer 0.24, shorter 0.12.

_Habitat._--Pacific, central area, Station 268, depth 2900 fathoms; the
same form also fossil in the rocks of Barbados.

Genus 128. _Lithomespilus_,[167] Haeckel, 1881, Prodromus, p. 450.

_Definition._--#Ellipsida# with simple ellipsoidal or oviform shell, the
main axis of which bears at one pole a single spine, at the other a bunch
of several spines.

{302}The genus _Lithomespilus_ differs from the closely allied
_Ellipsoxiphus_ in the further differentiation of both poles of the main
axis. One pole exhibits only a single polar spine, the other pole a group
of several spines, peculiarly grouped together. It differs from the similar
_Sphæromespilus_ (Pl. 14, figs. 12, 13) in the ellipsoidal form of the
shell.

1. _Lithomespilus phloginus_, n. sp. (Pl. 14, fig. 16).

Proportion of the major axis of the ellipsoid to the minor = 4 : 3. Shell
thick walled, with circular pores of different size, the breadth of which
equals that of the bars; twelve to fifteen pores on the half equator.
Surface smooth, with the exception of a circumpolar region covered with
numerous thick spines of unequal size, which surround the large single
polar spine and are curved like a bow against its axis. This larger polar
spine is straight, and equals in length the major axis of the shell. The
other and opposite polar spine is scarcely one-fourth as long, perfectly
simple, very stout, and of a three-sided pyramidal shape.

_Dimensions._--Longer axis of the ellipsoidal shell 0.08, shorter axis
0.06; pores 0.002 to 0.006, bars 0.003 to 0.005; length of the polar
spines--longer 0.08, shorter 0.02.

_Habitat._--Indian Ocean, near Madagascar, depth 1200 fathoms, Smith.

2. _Lithomespilus phlogoides_, n. sp. (Pl. 14, fig. 17).

Proportion of the major axis to the minor = 5 : 4. Shell very thick walled,
with roundish, double-contoured pores of different size and form, twice to
three times as broad as the bars; sixteen to eighteen pores on the half
equator. Surface smooth, with the exception of a circumpolar region covered
with numerous thin spines of unequal size, which surround the large single
polar spine and are curved like a bow against its axis. This larger polar
spine is straight, and equals half the size of the major axis of the shell;
the other polar spine (sometimes double, as in the figured specimen) is
much shorter, being scarcely one-fourth as long.

_Dimensions._--Longer axis of the shell 0.08, shorter axis 0.065; pores
0.003 to 0.006, bars 0.002 to 0.004; length of the polar spines--longer
0.04, shorter 0.01.

_Habitat._--Central area of the Pacific, Stations 270 to 272, depth 2425 to
2925 fathoms.

3. _Lithomespilus flammeus_, n. sp.

  _Stylosphæra species_, Bury, 1862, Polycystins of Barbados, pl. xi. fig.
  3.

Proportion of the major axis to the minor = 4 : 3. Shell thick walled, with
irregular, roundish pores, about as broad as the bars; ten to twelve pores
on the half equator. Surface spiny. Length of the conical straight spines
increasing towards the poles; each polar spine surrounded by a circumpolar
group of larger, somewhat curved spines. The larger polar spine equals in
length the major axis; the smaller is scarcely half as long. (The figure,
given by Bury, is not quite exact; there the spines are situated in the
pores, instead of between them. In my specimen the polar spines were not
branched.)

{303}_Dimensions._--Longer axis of the shell 0.12, shorter axis 0.09; pores
and bars 0.004 to 0.006; length of the polar spines--longer 0.12, shorter
0.06.

_Habitat._--Fossil in Barbados.

4. _Lithomespilus flammabundus_, n. sp. (Pl. 14, fig. 14).

Proportion of the major axis to the minor = 4 : 3. Shell thin walled, with
irregular, roundish pores, partly simple, partly composed of three to six
confluent pores; only six to eight pores on the half equator, twice to four
times as broad as the bars. Surface spiny. Length of the conical irregular
spines increasing towards the poles; each polar spine surrounded by a
flame-shaped, circumpolar area of longer spines; all large spines (also the
polar spines) curved or contorted at one pole and much stronger and more
numerous than at the other; length variable, often equal to the longer
axis.

_Dimensions._--Longer axis of the shell 0.12, shorter axis 0.09; pores
0.005 to 0.015, bars 0.003 to 0.005; length of the polar spines 0.1 to
0.15.

_Habitat._--Western part of the Tropical Atlantic, Station 347, depth 2250
fathoms.

Genus 129. _Lithapium_,[168] n. gen.

_Definition._--#Ellipsida# with simple ellipsoidal or pear-shaped shell;
with a single spine only situated at one pole of the main axis.

The genus _Lithapium_ represents a peculiar modification of
_Ellipsoxiphus_; one of the two opposite polar spines disappears by
reduction, and in this way only a single spine remains, at one pole of the
main axis. For this reason the shell assumes a characteristic pear-shape,
and may easily be confounded with some similar Monocyrtida (_Halicapsa_).

1. _Lithapium pyriforme_, n. sp. (Pl. 14, fig. 9).

Proportion of the longer axis to the shorter = 6 : 5. Shell thin walled,
with regular, circular pores, four times as broad as the bars; six to eight
on the half equator. Surface a little thorny. The single polar spines
three-sided pyramidal, as broad at the base as one mesh, about as long as
the radius of the shell. (In the specimen figured, there was on the
opposite pole a little rudiment of the other lost polar spine; it is
missing in other specimens.)

_Dimensions._--Major axis of the ellipsoidal shell 0.12, minor axis 0.1;
pores 0.02, bars 0.005; length of the single polar spine 0.05, basal
thickness 0.02.

_Habitat._--Central area of the Pacific, Station 266, depth 2750 fathoms.

2. _Lithapium halicapsa_, n. sp. (Pl. 14, fig. 8).

Proportion of the longer axis to the shorter = 6 : 5. Shell thin walled,
with irregular, lobed meshes, six to eight on the half equator, twice to
five times as broad as the bars; each mesh {304}composed of two to five
confluent roundish pores. Surface a little thorny. The single polar spine
pyramidal, as broad at the base as one mesh, one-third as long as the axis.

_Dimensions._--Major axis 0.12, minor axis 0.1; pores 0.01 to 0.02, bars
0.002 to 0.006; length of the single polar spine 0.03, basal thickness
0.02.

_Habitat._--Central area of the Pacific, Station 270, depth 2925 fathoms.

3. _Lithapium monocyrtis_, n. sp. (Pl. 14, fig. 10).

Proportion of the longer axis to the shorter = 7 : 6. Shell thick walled,
with irregular, lobed meshes, four to six on the half equator, three to six
times as broad as the bars; each mesh composed of three to six confluent
roundish pores. Surface quite smooth, without thorns. The single polar
spine pyramidal, as broad at the base as the largest mesh, half as long as
the radius. (This species is closely allied to the foregoing, but differs
in the smooth surface and the larger meshes.)

_Dimensions._--Major axis 0.15, minor axis 0.13; pores 0.01 to 0.03, bars
0.003 to 0.01; length of the single spine 0.04, basal thickness 0.03.

_Habitat._--Central area of the Pacific, Station 268, depth 2900 fathoms.

Genus 130. _Pipettella_,[169] n. gen.

_Definition._--#Ellipsida# with simple ellipsoidal shell, the main axis of
which is prolonged at the pole into two opposite hollow fenestrated tubes
of equal size and similar form.

The genus _Pipettella_ is distinguished from the other Ellipsida by two
hollow perforated tubes, which are directed in the longer axis of the
ellipsoidal shell and arise from opposite poles of this axis. It may be
derived from _Cenellipsis_ by prolongation of both poles of the main axis.
As the same peculiar production of two opposite latticed tubuli at the
poles of the main axis obtains in nearly all families of #Prunoidea#
(_Pipetta_, _Cannartus_, _Panarium_, _Zygartus_, &c.), it may possess a
peculiar value in this group.

1. _Pipettella fusiformis_, n. sp.

Shell spindle-shaped, thin walled, the two opposite tubes being conical and
not longer than the short transverse axis of the ellipsoidal shell; no
sharp demarcation between them. The two axes of the ellipsoid bear the
proportion of 3 : 2. Network of the shell and of the tubes equal, delicate,
regular, hexagonal, with circular apertures of equal size; fourteen to
sixteen on the half equator of the shell. Bars very thin. The shell of this
species is similar to that of _Cannartiscus amphiconiscus_ (Pl. 39, fig.
19), but possesses no equatorial stricture and no medullary shell.

_Dimensions._--Longer axis of the ellipsoid 0.18, shorter axis 0.12; length
of the tubes 0.1, their basal breadth 0.05; pores of the network 0.01, bars
0.001.

_Habitat._--Northern Pacific, Station 244, depth 2900 fathoms.

{305}2. _Pipettella tubulosa_, n. sp.

Shell ellipsoidal, thin walled, distinctly separated from the two opposite
tubes, which are cylindrical, longer than the main axis of the ellipsoid,
and one-sixth as broad as the shorter axis. The longer axis of the
ellipsoid bears to the shorter the proportion of 5 : 4. Network of the
shell and of the tubes equal, regular, with very small circular pores,
about as broad as the bars; sixteen to eighteen pores on the half equator
of the shell.

_Dimensions._--Longer axis of the ellipsoid 0.15, shorter axis 0.12; length
of the tubes 0.16 to 0.2, breadth of them 0.02; pores of the network 0.003,
bars 0.003.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.

3. _Pipettella elongata_, n. sp.

Shell ellipsoidal, thick walled, distinctly separated from both opposite
tubes, which are cylindrical, much prolonged, twice to three times as long
as the main axis of the ellipsoid, and one-fifth as broad as the shorter
axis. Both axes of the ellipsoid bear the proportion of 3 : 2. Network of
the shell and of the tubes irregular with small rounded pores of different
size, separated by broader bars (often twice to three times as broad), four
to six pores on the half equator of the shell. (This species somewhat
recalls _Solenosphæra serpentina_, Pl. 7, fig. 7; but the tubes are
straight, not contorted.)

_Dimensions._--Longer axis of the ellipsoid 0.2, shorter axis 0.14; length
of the tubes 0.4 to 0.5, breadth 0.03; pores of the network 0.001 to 0.002,
bars 0.003 to 0.004.

_Habitat._--Central area of the Pacific, Station 271, depth 2425 fathoms.

4. _Pipettella prismatica_, n. sp. (Pl. 39, fig. 6).

Shell ellipsoidal, thick walled, distinctly marked off from the two
opposite tubes, which are longer than its main axis and as broad as
one-fifth of it; they are nearly four-sided prismatic, with four strong
ribs or edges; these are directed parallel to the main axis, in two
meridian planes, perpendicular to one another. The wall of the shell is
thickened in the equatorial plane, so as to form a slight stricture on the
inside, separating its two halves. Both axes of the ellipsoid bear the
proportion of 7 : 6. Network regular, with circular pores, somewhat broader
than the bars. The meshes of the shell (fourteen to sixteen on the half
equator) are twice as great as those of the tubes, which are arranged in
two longitudinal rows between every two ribs (there being eight
longitudinal rows on the whole tube). This species is very remarkable for
the rudimentary internal equatorial stricture of the shell (transition to
the genus _Cannartus_, Pl. 39, fig. 10), and by the four edges of the
tubes, which indicate two of the dimensive axes, the third being
represented by the main axis.

_Dimensions._--Longer axis of the ellipsoid 0.14, shorter axis 0.12; length
of the tubes 0.15 to 0.16, breadth 0.03; pores of the shell 0.008 to 0.01,
pores of the tubes 0.004.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.

{306}Family XII. #DRUPPULIDA#, Haeckel, 1882 (Pls. 15, 16, 17, 39).

_Definition._--#Prunoidea# with ellipsoidal, latticed (not spongy) shell,
composed of two or more concentric shells; a simple or double cortical
shell enclosing one or two internal concentric shells (medullary shells),
without equatorial stricture. Central capsule ellipsoidal or cylindrical,
without annular equatorial constriction.

The family #Druppulida# differs from the Ellipsida only in the possession
of a simple or double medullary shell, which is enclosed in the centre of
the central capsule, and connected with the ellipsoidal cortical shell
(lying outside it) by radial beams, perforating the membrane of the
capsule. The Druppulida exhibit therefore the same relation to the
Ellipsida that the Dyosphærida among the #Sphæroidea# bear to the
Monosphærida. The cortical shell may be simple or multiple. The whole
fenestrated shell is thus composed of a variable number (two at least) of
concentric shells, which are connected by radial beams.

_The Medullary Shell_--enclosed in the centre of the central capsule--is
either simple or double, and composed of two small concentric shells. Their
form is either spherical, or ellipsoidal, or lenticular. If the medullary
shell be ellipsoidal, the main axis of the ellipsoid is the same as in the
cortical shell. Sometimes the inner medullary shell is spherical, the outer
ellipsoidal or lenticular. If the medullary shell be lenticular (arising
from both poles of the main axis) its vertical axis is also identical with
that of the cortical shell (Pl. 39, fig. 5).

_The Radial Beams_, which connect the medullary and cortical shell, are
either developed in all possible directions (Pls. 16, 17), or limited to
the equatorial plane, more rarely to the meridional plane. Sometimes the
connection is produced only by two opposite beams which lie in the minor or
equatorial axis (Pl. 39, figs. 3, 7, 8); more rarely in the major or
meridional axis (Pl. 17, figs. 7, 8).

_The Cortical Shell_ is constantly ellipsoidal, rarely with modifications,
similar to those which appear in the simple shell of some Ellipsida. As a
rule it is simple, rarely composed of two or more (sometimes six or more)
concentric ellipsoidal shells (in _Cromyodruppa_ and _Cromyocarpus_). The
outer surface is commonly smooth, more rarely covered with radial spines
(in _Druppocarpus_, _Prunocarpus_, &c.). In the majority peculiar polar
appendages are developed at both poles of the main axis, these being
prolongations of them, either in the form of hollow fenestrated tubes
(_Pipetta_, _Pipettaria_, Pl. 39, figs. 7, 8), or solid strong spines. The
two polar spines are either equal in size and similar in form (as in
_Lithatractus_, _Stylatractus_) or unequal (as in _Druppatractus_,
_Xiphatractus_, Pls. 16, 17).

The most primitive of all Druppulida is _Druppula_, with simple medullary
shell and simple cortical shell (Pl. 39, fig. 3); _Prunulum_ differs from
it only in the possession {307}of a double medullary shell (Pl. 39, fig.
4). From these two genera all other forms of the subfamily may be derived.

_The Central Capsule_ of the Druppulida is constantly ellipsoidal, larger
than the concentric enclosed medullary shells, smaller than the surrounding
cortical shell; it is separated from the inner surface of the latter by a
thinner or thicker jelly-mantle.

_Synopsis of the Genera of the Druppulida._

  -------------------------------------------------------------------------
  Cortical shell without polar appendages (neither solid spines nor hollow
  tubes at the poles of the main axis).
  -------------------------------------------------------------------------
                 {              {Surface
                 {Medullary     { smooth,  131. _Druppula_.
                 { shell simple.{
                 {              {Surface
  Cortical shell {              { spiny,   132. _Druppocarpus_.
   simple,       {
   ellipsoidal.  {              {Surface
                 {Medullary     { smooth,  133. _Prunulum_.
                 { shell double.{
                 {              {Surface
                 {              { spiny,   134. _Prunocarpus_.

  Cortical shell }Medullary     {Surface
   composed of   } shell        { smooth,  135. _Cromyodruppa_.
   two or more   } double.      {
   concentric    }              {Surface
   shells.       }              { spiny,   136. _Cromyocarpus_.
  -------------------------------------------------------------------------
  Two opposite solid spines, arising from the poles of the main axis.
  -------------------------------------------------------------------------
               {          {Both polar
               {Medullary { spines equal,  137. _Lithatractus_.
               { shell    {
               { simple.  {Both polar
  Cortical     {          { spines
   shell       {          { unequal,       138. _Druppatractus_.
   simple,     {
   ellipsoidal.{          {Both polar
               {          { spines equal,  139. _Stylatractus_.
               {Medullary {
               { shell    {Both polar
               { double.  { spines
               {          { unequal,       140. _Xiphatractus_.

  Cortical shell composed of two or more
   concentric shells; medullary shell
   double; both polar spines equal,        141. _Cromyatractus_.
  -------------------------------------------------------------------------
  Two opposite hollow fenestrated tubes, arising from the poles of the
  main axis.
  -------------------------------------------------------------------------
  Medullary shell simple,                  142. _Pipetta_.

  Medullary shell double,                  143. _Pipettaria_.

Genus 131. _Druppula_,[170] n. gen.

_Definition._--#Druppulida# with simple ellipsoidal, cortical shell, and
simple medullary shell, without spines or polar tubes.

The genus _Druppula_, as the simplest form of the Druppulida, may be
regarded as the common ancestral form of this subfamily. It may be derived
phylogenetically either {308}from _Carposphæra_ by prolongation of one
axis, or from _Cenellipsis_ by duplication of the fenestrated shell. The
outer (or cortical) shell is always more or less ellipsoidal; the inner (or
medullary) shell also is sometimes ellipsoidal, sometimes spherical. Both
shells are concentric, connected by a variable number of radial beams.
Compare _Haliomma oblongum_, Harting, 1863, L. N. 18, p. 15, pl. 2, fig.
42.

Subgenus 1. _Druppuletta_, Haeckel.

_Definition._--Pores of the cortical shell regular, hexagonal, or circular.

1. _Druppula drupa_, n. sp.

Cortical shell thin walled, with smooth surface and regular network; both
its axes bear the proportion of 4 : 3. Pores regular, hexagonal, three
times as broad as the bars; twelve to fifteen on the half equator.
Medullary shell spherical, about one-third as broad as the cortical shell.

_Dimensions._--Major axis of the ellipsoidal cortical shell 0.1 to 0.12,
minor axis 0.08 to 0.09; pores 0.06, bars 0.02; diameter of the medullary
shell 0.03.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms; also
fossil in Barbados.

2. _Druppula pandanus_, n. sp. (Pl. 39, fig. 3).

Cortical shell thin walled, somewhat rough, with regular network; both its
axes bear the proportion of 3 : 2. Pores subregular, circular, hexagonally
framed, one and a half times as broad as the elevated bars; ten to twelve
on the half equator. Medullary shell spherical, one-fourth as broad as the
cortical shell.

_Dimensions._--Major axis of the cortical shell 0.16 to 0.17, minor axis
0.11 to 0.12; pores 0.01, bars 0.007; diameter of the medullary shell
0.035.

_Habitat._--Pacific, central area, Station 268, depth 2900 fathoms.

3. _Druppula cocos_, n. sp.

Cortical shell thick walled, somewhat rough, with regular network;
proportion of both axes = 6 : 5. Pores regular, circular, hexagonally
framed, quite as broad as the elevated bars; fourteen to sixteen on the
half equator. Medullary shell ellipsoidal (with longitudinal main axis),
nearly half as large as the cortical shell.

_Dimensions._--Major axis of the cortical shell 0.07 to 0.08, minor axis
0.6 to 0.65; pores and bars 0.003 to 0.004; diameter of the medullary shell
0.03 and 0.035.

_Habitat._--Western Tropical Pacific, Station 222, surface, Indian Ocean,
Ceylon, Haeckel.

4. _Druppula phoenix_, n. sp.

Cortical shell thick walled, smooth, with regular network; proportion of
both axes = 5 : 4. Pores regular, circular, hexagonally lobulate (in the
same manner as in _Stauroxiphus gladius_, {309}Pl. 15, fig. 7), three times
as broad as the bars; ten to twelve on the half equator. Medullary shell
ellipsoidal (with longitudinal main axis), one-third as broad as the
cortical shell.

_Dimensions._--Major axis of the cortical shell 0.1, minor axis 0.08; pores
0.009, bars 0.003; axis of the medullary shell 0.03 and 0.025.

_Habitat._--Mediterranean, Smyrna, Haeckel, surface.

5. _Druppula areca_, n. sp.

Cortical shell thin walled, with smooth surface and regular network; both
its axes bear the proportion of 4 : 3. Pores regular, circular, four times
as broad as the bars; fifteen to eighteen on the half equator. Medullary
shell spherical, half as broad as the cortical shell.

_Dimensions._--Major axis of the ellipsoidal cortical shell 0.12 to 0.14,
minor axis 0.1 to 0.11; pores 0.008, bars 0.002; diameter of the medullary
shell 0.05 to 0.06.

_Habitat._--Indian Ocean, off Bombay, Haeckel.

6. _Druppula ovata_, Haeckel.

  _Haliomma ovatum_, Ehrenberg, 1854, Mikrogeol., pl. xx. I. fig. 20.

  _Haliomma ovatum_, Haeckel, 1862, Monogr. d. Radiol., p. 432.

Cortical shell thin walled, with smooth surface and regular network;
proportion of both axes = 3 : 2. Pores regular, circular, three times as
broad as the bars; nine to ten on the half equator. Medullary shell
spherical, one-third as broad as the cortical shell.

_Dimensions._--Major axis 0.08 to 0.1, minor axis 0.05 to 0.06; pores
0.003, bars 0.001; diameter of the medullary shell 0.02.

_Habitat._--Fossil in the Tertiary rocks of the Mediterranean coast, Greece
(Zante), Ehrenberg; Sicily (Caltanisetta), Haeckel.

7. _Druppula caryota_, n. sp.

Cortical shell thick walled, with rough surface and regular network;
proportion of both axes = 5 : 4. Pores regular, circular, twice as broad as
the bars; sixteen to twenty on the half equator. Medullary shell
ellipsoidal, one-third as large as the cortical shell.

_Dimensions._--Major axis 0.2 to 0.22, minor 0.16 to 0.18, pores 0.008,
bars 0.004; axes of the medullary shell 0.07 and 0.055.

_Habitat._--Pacific, central area, Stations 266 to 268, depth 2700 to 2900
fathoms.

Subgenus 2. _Druppulissa_, Haeckel.

_Definition._--Pores of the cortical shell irregular, of different form or
size, usually subcircular or roundish, sometimes lobed or compound.

{310}8. _Druppula nucula_, n. sp.

Cortical shell thin walled, smooth, with irregular network; its two axes
bear the proportion 3 : 2. Pores subcircular or irregular, roundish, twice
to four times as broad as the bars; fifteen to twenty on the half equator.
Medullary shell spherical, about one-third as broad as the cortical shell.

_Dimensions._--Major axis of the cortical shell 0.15 to 0.2, minor axis 0.1
to 0.14; pores 0.006 to 0.012, bars 0.03; diameter of the medullary shell
0.04.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.

9. _Druppula elliptica_, Haeckel.

  _Haliomma ellipticum_, Stöhr, 1880, Palæontogr., _loc. cit._, p. 88, Taf.
  i. fig. 11.

Cortical shell thin walled, rough, or thorny, with irregular network;
proportion of the axes = 3 : 2. Pores subcircular or irregular, roundish,
about as broad as the bars; ten to twelve on the half equator. Medullary
shell half as broad as the cortical shell, irregularly polyhedral (with
crooked beams in its interior).

_Dimensions._--Major axis 0.15, minor 0.06; pores and bars 0.006; diameter
of the medullary shell 0.03.

_Habitat._--Fossil in the Tertiary rocks of Sicily: Grotte (Stöhr),
Caltanisetta (Haeckel).

10. _Druppula prunum_, n. sp.

Cortical shell thick walled, smooth, with irregular network; proportion of
the axes = 5 : 4. Pores subcircular or irregular, roundish, three to four
times as broad as the bars; seven to eight on the half equator; every pore
is closed at the bottom by a thin membrane, perforated by four to six
irregular pores (like _Stylatractus sethoporus_, Pl. 17, fig. 3). Medullary
shell spherical, one-third as broad as the cortical shell.

_Dimensions._--Major axis 0.2, minor axis 0.16; pores 0.03, bars 0.01;
small enclosed porules 0.01; diameter of the medullary shell 0.05.

_Habitat._--Mediterranean, surface, Portofino near Genoa, Haeckel.

11. _Druppula oliva_, n. sp.

Cortical shell thick walled, rough, with irregular network; proportion of
the axes = 5 : 4. Pores irregular, roundish, three to four times as broad
as the bars; lobed or composed of several conjugated porules (as in
_Lithapium halicapsa_, Pl. 14, fig. 8); five to six large pores on the half
equator. Medullary shell ellipsoidal, about one-third as broad as the
cortical shell.

_Dimensions._--Major axis of the cortical shell 0.15, minor 0.12; pores
0.02 to 0.03, bars 0.007; diameter of the medullary shell 0.04.

_Habitat._--Mediterranean (Corfu), Canary Islands (Lanzerote), Haeckel.

{311}Genus 132. _Druppocarpus_,[171] n. gen.

_Definition._--#Druppulida# with simple ellipsoidal cortical shell and
simple medullary shell, with numerous radial spines, without polar tubes.

The genus _Druppocarpus_ differs from _Druppula_ only in the radial spines,
which arise between the pores of the cortical shell, and therefore exhibits
the same relation to it that _Ellipsidium_ bears to _Cenellipsis_, or
_Prunocarpus_ to _Prunulum_.

Subgenus 1. _Druppocarpetta_, Haeckel.

_Definition._--Network of the cortical shell regular, with meshes of equal
size and similar form.

1. _Druppocarpus ananassa_, n. sp.

Cortical shell thin walled, with regular, circular, hexagonally framed
pores, of about the same breadth as the elevated bars; fourteen to sixteen
on the half equator. From each hexagon-corner (between every three pores)
arises a short thin radial spine, about as long as two pores, three-sided
pyramidal at the base. Proportion of both cortical axes = 4 : 3. Medullary
shell spherical, half as broad as the cortical shell. (Greatly resembles
_Druppula pandanus_, Pl. 39, fig. 3, but differs in the larger medullary
shell and the spines on the surface.)

_Dimensions._--Major axis of the ellipsoidal cortical shell 0.16, minor
0.12; pores and bars 0.006; length of the radial spines 0.02; diameter of
the medullary shell 0.06.

_Habitat._--South Pacific, Station 289, surface.

2. _Druppocarpus castanea_, n. sp.

Cortical shell thin walled, with regular circular pores (without hexagonal
frames), of about the same breadth as the bars; twelve to fourteen on the
half equator. Between every three meshes arise a short conical spine with
bristle-like apex, twice to four times as long as one pore. Proportion of
both cortical axes = 3 : 2. Medullary shell spherical, one-third as broad
as the cortical. (Resembles very closely the spherical _Haliomma castanea_,
Haeckel, figured in my Monograph. pl. xxiv. fig. 4.)

_Dimensions._--Major axis 0.15, minor axis 0.1; pores and bars 0.005;
length of the radial spines 0.01 to 0.02; medullary shell 0.035.

_Habitat._--North Atlantic, surface; Canary Islands, Lanzerote, Haeckel.

Subgenus 2. _Druppocarpissa_, Haeckel.

_Definition._--Network of the cortical shell irregular, with meshes of
different size or form.

{312}3. _Druppocarpus chamaerops_, n. sp.

Cortical shell thin walled, with irregular, roundish, or subcircular pores
of very different size, twice to six times as broad as the thin bars; eight
to twelve on the half equator. Between them arise numerous thin,
bristle-like radial spines, about half as long as the equatorial axis, and
equal to the diameter of the spherical medullary shell; pores of the latter
subregular, circular, very small. (Resembles _Prunocarpus artocarpus_, Pl.
39, fig. 5, but differs in the simple spherical medullary shell.)

_Dimensions._--Major axis 0.12, minor 0.09; meshes 0.005 to 0.02, bars
0.003; length of the radial spines 0.05; diameter of the medullary shell
0.04.

_Habitat._--Mediterranean, in the Strait of Gibraltar, Algesiras, Haeckel,
surface.

4. _Druppocarpus borassus_, n. sp.

Cortical shell thick walled, with irregular, roundish, or subcircular
pores, three to five times as broad as the bars; twelve to fifteen on the
half equator. Irregularly scattered on the surface about twenty to thirty
short conical spines; their length equals their basal breadth and the
diameter of the largest pores.  Medullary shell ellipsoidal, half as large
as the cortical.

_Dimensions._--Major axis 0.1, minor 0.08; pores 0.006 to 0.01, bars 0.002;
length and thickness of the radial spines 0.01; axes of the medullary shell
0.05 and 0.04.

_Habitat._--Pacific, central area, Station 268, depth 2900 fathoms.

5. _Druppocarpus corypha_, n. sp.

Cortical shell thick walled, with irregular, funnel-like, roundish pores,
scarcely as broad as the bars; sixteen to twenty on the half equator.
Irregularly scattered on the surface about fifteen to twenty three-sided
pyramidal radial spines, half as long as the equatorial axis, and as the
diameter of the medullary shell.

_Dimensions._--Major axis 0.17, minor 0.14; pores and bars 0.003 to 0.009;
length of the radial spines 0.08; diameter of the medullary shell 0.09.

_Habitat._--Fossil in the Tertiary rocks of the Nicobars, Haeckel.

Genus 133. _Prunulum_,[172] n. gen.

_Definition._--#Druppulida# with simple ellipsoidal cortical shell and
double medullary shell; without spines or polar tubes.

The genus _Prunulum_ differs from _Druppula_ in the double (not simple)
medullary shell, which is sometimes spherical, sometimes ellipsoidal; it
may be derived either from _Druppula_ by duplication of the medullary
shell, or from _Thecosphæra_ by prolongation of one axis.

{313}Subgenus 1. _Prunuletta_, Haeckel.

_Definition._--Network of the cortical shell regular, with meshes of equal
size and similar form.

1. _Prunulum frugulum_, n. sp.

Cortical shell thin walled, smooth, with regular, hexagonal pores, three
times as broad as the bars; ten to twelve on the half equator. Proportion
of the major axis of the ellipsoid to the minor = 4 : 3. Both medullary
shells spherical. (Differs from _Druppula drupa_ almost entirely in the
double medullary shell.)

_Dimensions._--Major axis of the ellipsoidal cortical shell 0.12, minor
0.09; pores 0.006, bars 0.002; diameter of both medullary shells 0.05 and
0.03.

_Habitat._--Pacific, central area, Station 266, depth 2750 fathoms.

2. _Prunulum cerasum_, n. sp.

Cortical shell thick walled, smooth, with circular, hexagonally framed
pores, of the same breadth as the bars; sixteen to eighteen on the half
equator. Proportion of the two axes of the ellipsoid = 5 : 4. Both
medullary shells spherical. (The cortical shell resembles that of _Pipetta
tuba_, Pl. 39, fig. 7, without the polar tubes.)

_Dimensions._--Major axis 0.15, minor 0.12; pores and bars 0.007; diameter
of the medullary shells 0.08 and 0.04.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

3. _Prunulum amygdalum_, n. sp.

Cortical shell thick walled, smooth, with regular, circular, hexagonally
lobulated pores, three times as broad as the bars; twelve to fourteen on
the half equator (of the same form as in _Druppula phoenix_ and in
_Stauroxiphos gladius_, Pl. 15, fig. 7). Proportion of the two axes =
6 : 5. Inner medullary shell spherical, outer ellipsoidal.

_Dimensions._--Major axis 0.12, minor 0.1; pores 0.009, bars 0.003;
diameter of the medullary shells 0.07 and 0.04.

_Habitat._--Mediterranean (Corfu), surface.

4. _Prunulum coccymelium_ (Pl. 39, fig. 4).

Cortical shell thin walled, slightly rough, with regular, circular pores,
twice as broad as the bars; twelve to fifteen on the half equator.
Proportion of both axes = 4 : 3. Both medullary shells spherical.

_Dimensions._--Major axis 0.12, minor 0.09; pores 0.006, bars 0.003;
diameter of the medullary shells 0.06 and 0.03.

_Habitat._--Pacific, central area, Station 273, depth 2350 fathoms.

{314}5. _Prunulum crenatum_, Haeckel.

  ? _Haliomma crenatum_, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 36.

  _Actinomma crenatum_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 94, Taf.
  iii. fig. 3.

  _Caryolithis crenata_, Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d.
  Wiss. Berlin, p. 43.

Cortical shell thick walled, slightly rough or thorny, with small, regular,
circular pores, of the same breadth as the bars; sixteen to eighteen on the
half equator. Proportion of the two axes = 4 : 3. Both medullary shells
ellipsoidal. (The figure of Stöhr represents exactly the fossil form, as I
have observed it myself in the Caltanisetta rocks, whilst the figure of
Ehrenberg is inaccurate and doubtful. The same form, somewhat variable in
size and in the number of the pores, I have also observed in the Pacific
ooze.)

_Dimensions._--Major axis 0.14 to 0.17, minor 0.1 to 0.13; pores and bars
0.006; main axes of the medullary shells 0.09 and 0.03.

_Habitat._--Fossil in the Tertiary rocks of Sicily (Grotte and
Caltanisetta); living in the Central Pacific, Station 268, depth 2900
fathoms.

6. _Prunulum triplex_, Haeckel.

  _Haliomma triplex_, Ehrenberg, 1854, Microgeol., Taf. xxxvB. fig. Biv.,
  q.

  _Actinomma triplex_, Haeckel, 1862, Monogr. d. Radiol., p. 444.

Cortical shell thin walled, covered with numerous very thin, short,
bristle-like spines. Pores small, regular, circular, of the same breadth as
the bars; fourteen to sixteen on the half equator. Proportion of the two
axes = 3 : 2. Both medullary shells ellipsoidal. The description of
Ehrenberg--as is very often the case--is quite incongruent with his figure.
From a combination of both I give here the diagnosis of a deep-sea species,
which is possibly identical with it. The velvet-like covering of very short
and thin bristles is peculiarly characteristic of this species.

_Dimensions._--Major axis 0.1, minor 0.065; pores and bars 0.004; main axes
of the medullary shells 0.04 and 0.02.

_Habitat._--North Atlantic, 1800 fathoms, Ehrenberg; Station 353, depth
2965 fathoms.

Subgenus 2. _Prunulissa_, Haeckel.

_Definition._--Network of the cortical shell irregular, with meshes of
different form or size (usually roundish, but sometimes lobed or compound).

7. _Prunulum persicum_, n. sp.

Cortical shell thick walled, with smooth surface and irregular, roundish,
double-contoured pores, twice to four times as broad as the bars; eight to
ten on the half equator. Some of the pores are simple, often subcircular,
others lobed, i.e., composed of from two to three confluent pores as in
_Amphisphæra pluto_ (Pl. 17, fig. 7). Proportion of the two axes = 3 : 2.
Both medullary shells ellipsoidal (or the inner spherical).

{315}_Dimensions._--Major axis 0.12, minor 0.08; pores 0.06 to 0.012, bars
0.003; main axes of the medullary shells 0.05 and 0.025.

_Habitat._--Indian Ocean, between Socotra and Ceylon, surface, Haeckel.

8. _Prunulum fenestratum_, Haeckel.

  _Actinomma fenestratum_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 94, Taf.
  iii. fig. 2.

Cortical shell thick walled, rough, with irregular, roundish pores, once to
three times as broad as the bars; twelve to fourteen on the half equator.
Proportion of the two axes = 9 : 8. Both medullary shells ellipsoidal. (The
pores in Stöhr's description are by mistake called "regular"; in the figure
they are very irregular, as also in the fossil specimens observed by
myself. Between the cortical pores arise very short irregular thorns.)

_Dimensions._--Major axis 0.12 to 0.15, minor 0.1 to 0.12; pores 0.003 to
0.01, bars 0.003; main axis of the outer medullary shell 0.07 to 0.09, of
the inner 0.03 to 0.04.

_Habitat._--Fossil in the Tertiary rocks of Sicily; Grotte, Stöhr,
Caltanisetta, Haeckel.

9. _Prunulum pyrenium_, n. sp.

Cortical shell very thick walled, smooth, with large irregular, roundish
pores, three to four times as broad as the bars; six to eight on the half
equator. The bottom of each funnel-like pore is closed by a thin siliceous
membrane, perforated by three to five irregular roundish pores. Proportion
of the two axes = 4 : 3. Both medullary shells ellipsoidal. (Closely
resembles _Stylatractus sethoporus_, Pl. 17, figs. 2, 3, but is devoid of
the polar spines.)

_Dimensions._--Major axis 0.16, minor 0.12; pores 0.015 to 0.02, bars
0.005; porules 0.01; main axes of the medullary shells 0.07 and 0.03.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.

Genus 134. _Prunocarpus_,[173] n. gen.

_Definition._--#Druppulida# with simple ellipsoidal cortical shell and
double medullary shell, with numerous radial spines, but without polar
tubes.

The genus _Prunocarpus_ differs from _Prunulum_ only in the radial spines
of the cortical shell, and exhibits therefore the same relation to it that
_Druppocarpus_ bears to _Druppula_. While in the latter the medullary shell
is simple, in the former it is double.

Subgenus 1. _Prunocarpetta_, Haeckel.

_Definition._--Network of the cortical shell regular, with meshes of equal
size and similar form.

{316}1. _Prunocarpus datura_, n. sp.

Cortical shell thick walled, with regular, circular pores, twice as broad
as the bars; ten to twelve on the half equator. Between every three meshes
arises a short conical spine, twice to three times as long as one pore.
Both medullary shells spherical. (Differs mainly from _Ellipsidium datura_
and from _Druppocarpus castanea_ in the double medullary shell. The outer
network resembles _Haliomma castanea_, figured 1862 in my Monograph, Taf.
xxiv. fig. 4.)

_Dimensions._--Major axis of the ellipsoid 0.16, minor 0.12; pores 0.012,
bars 0.006; length of the radial spines 0.03; diameter of the medullary
shells 0.06 and 0.04.

_Habitat._--North Atlantic, Færöe Channel, John Murray, surface.

2. _Prunocarpus sparganium_, n. sp.

Cortical shell thick walled, with very small, numerous, regular, circular
pores, of the same size as the bars; forty to fifty on the half equator.
Between them over the entire surface occur small conical spines.
Irregularly scattered over the surface ten to twenty larger conical spines,
three to six times as thick at the base as one pore, one-fourth to one-half
as long as the main axis. Both medullary shells ellipsoidal.

_Dimensions._--Major axis of the cortical shell 0.16, of the outer
medullary shell 0.11, of the inner 0.06; equatorial axis of the first shell
0.12, of the second 0.08, of the third 0.04; pores and bars on an average
0.005; length of the spines 0.05 to 0.1, basal breadth 0.02 to 0.03.

_Habitat._--Fossil in the Barbados deposits (Haeckel).

Subgenus 2. _Prunocarpilla_, Haeckel.

_Definition._--Network of the cortical shell irregular, with meshes of
different size or form.

3. _Prunocarpus artocarpium_, n. sp. (Pl. 39, fig. 5).

Cortical shell thin walled with irregular, roundish pores of very different
sizes, twice to nine times as broad as the thin bars; ten to fifteen on the
half equator. Between them arise numerous bristle-shaped, radial spines,
with conical base, on an average one-fourth to two-thirds as long as the
equatorial axis. The outer medullary shell, with irregular, roundish pores,
presents a transverse ellipsoid, its main axis lying in the equatorial axis
of the cortical shell, whilst its equatorial axis corresponds to the main
axis of the latter. Inner medullary shell very small, spherical, with very
small pores.

_Dimensions._--Major axis of the cortical shell 0.14, of the outer
medullary shell 0.05; minor axis of the former 0.1, of the latter 0.035;
diameter of the inner medullary shell 0.014; pores of the cortical shell
0.005 to 0.02, bars 0.002; length of the radial spines 0.02 to 0.06.

_Habitat._--Indian Ocean, surface; Ceylon, Belligemma, Haeckel.

{317}4. _Prunocarpus melocactus_, n. sp.

Cortical shell thick walled, with irregular, roundish pores, twice to five
times as broad as the bars; eighteen to twenty-four on the half equator.
Between them arise over the entire surface small conical thorns, not longer
than the largest pores. Irregularly scattered over the surface twenty to
thirty strong, conical, radial spines, about half as long as the main axis,
as broad at the base as a large pore.  Both medullary shells ellipsoidal,
their main axis identical with that of the cortical shell.

_Dimensions._--Major axis of the outer shell 0.18, of the middle 0.09, of
the inner 0.05; minor axis of the first 0.14, of the second 0.07, of the
third 0.04; pores of the cortical shell 0.006 to 0.02, bars 0.004; length
of the spines 0.1, basal breadth 0.01.

_Habitat._--Pacific, central area, Station 268, depth 2900 fathoms; also
fossil in the Tertiary rocks of Sicily; Caltanisetta, Haeckel.

Genus 135. _Cromyodruppa_,[174] n. gen.

_Definition._--#Druppulida# with four or more concentric shells (two
medullary and two or more cortical shells), without spines or polar tubes.

The genus _Cromyodruppa_ is characterised by the multiplication of the
concentric fenestrated shell, which is composed of two medullary shells
(enclosed in the central capsule) and two or more cortical shells (outside
it). The former may be either spherical or ellipsoidal. The latter are
always ellipsoidal, and in this it differs from _Cromyosphæra_. Probably
_Cromyodruppa_ has arisen from _Prunulum_ by secondary apposition of more
cortical envelopes.

Subgenus 1. _Cromyodruppium_, Haeckel.

_Definition._--Shell composed of four concentric shells, two medullary and
two cortical.

1. _Cromyodruppa cepa_, n. sp.

Shell composed of two ellipsoidal, cortical, and two spherical medullary
shells. Proportion of the main axes of the four shells = 1 : 2 : 4 : 5.
Network of all four shells nearly of the same form, subregular, with
circular pores of almost equal size in every shell. The absolute size of
the pores increases from the innermost to the outermost shell, but the
breadth of the bars does not increase in a similar degree. The bars of the
outermost shell are only twice as broad as those of the innermost; but the
pores are three to four times larger. Surface of all four shells smooth.
(The shell greatly resembles that of _Cromyatractus tetraphractus_, Pl. 15,
fig. 2, but is devoid of polar spines; it differs also in the spherical
form of both medullary shells and their relative size.)

{318}_Dimensions._--Main axes of the four shells--(A) innermost 0.035, (B)
second 0.08, (C) third 0.15, (D) outermost 0.2; their equatorial axes--(A)
0.03, (B) 0.08, (C) 0.12, (D) 0.16; pores 0.004 to 0.016, bars 0.002 to
0.004.

_Habitat._--Western Tropical Pacific, Station 198, depth 2150 fathoms.

Subgenus 2. _Caryodruppula_, Haeckel.

_Definition._--Shell composed of five or more concentric shells (two
medullary and three or more cortical).

2. _Cromyodruppa mango_, n. sp.

Shell composed of six ellipsoidal, concentric shells, two medullary and
four cortical. Proportion of their main axes = 2 : 3 : 8 : 11 : 14 : 18.
Network of the two medullary shells and of the innermost cortical shell
subregular, with subcircular pores, about the same breadth as the bars.
Network of the three outer cortical shells more lax, with larger,
irregular, roundish pores, twice to six times as broad as the bars. The
size of the pores and bars increases gradually from the innermost to the
outermost shell. Surface smooth.

_Dimensions._--Main axis of the six shells--(A) innermost 0.04, (B) 0.06,
(C) 0.16, (D) 0.22, (E) 0.28, (F) 0.35; their equatorial axes--(A)
innermost 0.03, (B) 0.05, (C) 0.12, (D) 0.16, (E) 0.2, (F) 0.25; pores
0.003 to 0.02, bars 0.003 to 0.005.

_Habitat._--Indian Ocean, surface; Matura, Ceylon, Haeckel.

Genus 136. _Cromyocarpus_,[175] n. gen.

_Definition._--#Druppulida# with four or more concentric shells (two
medullary and two or more cortical shells), with numerous radial spines,
but without polar tubes.

The genus _Cromyocarpus_ differs from _Cromyodruppa_ only in the
development of numerous large radial spines which start from the outer
surface of the shell. It exhibits therefore the same relation to the latter
that _Prunocarpus_ bears to _Prunulum_, or _Druppocarpus_ to _Druppula_. It
differs from both in the multiplication of the cortical shell.

1. _Cromyocarpus quadrifarius_, n. sp.

Shell composed of four concentric shells, two ellipsoidal cortical shells,
and two spherical medullary shells. Proportion of their main axes =
10 : 8 : 3 : 2. Pores of the two cortical shells irregular, roundish, twice
to four times as broad as the bars. Pores of the two medullary shells
subregular, circular, about the same size as the bars. Outer surface
covered with numerous conical radial spines, about half as long as the main
axis, half as broad at the base as the innermost shell.

{319}_Dimensions._--Major axis of the outer cortical shell 0.2, of the
inner 0.15; equatorial axis of the former 0.16, of the latter 0.12;
diameter of the outer medullary shell 0.06, of the inner 0.04; pores of the
cortical shells 0.01 to 0.02, of the medullary shells 0.004 to 0.008, bars
0.003 to 0.006; length of the radial spines 0.1, basal breadth 0.02.

_Habitat._--Indian Antarctic Ocean, Station 157, depth 1950 fathoms.

Genus 137. _Lithatractus_,[176] n. gen.

_Definition._--#Druppulida# with simple ellipsoidal cortical shell and
simple medullary shell, with two large opposite polar spines in the main
axis of equal size and similar form.

The genus _Lithatractus_, rich in common and widely distributed species,
begins the series of those Druppulida which are characterised by peculiar
polar spines at both poles of the main axis. It repeats the formation of
_Stylosphæra_ and _Ellipsostylus_, and differs from the former in the
ellipsoidal form of the cortical shell, from the latter in the possession
of a medullary shell. Formerly all these forms were united in the one genus
_Stylosphæra_ (see above, p. 121).

Subgenus 1. _Lithatractara_, Haeckel.

_Definition._--Network of the outer shell regular or subregular, with
meshes of nearly equal size and similar form; surface smooth, without
thorns or papillæ.

1. _Lithatractus hexagonalis_, n. sp.

Outer shell thin walled, smooth, without thorns or papillæ, with regular
delicate network; the meshes hexagonal, three to four times as broad as the
thin bars; ten to twelve on the half equator. Proportion of the major axis
of the ellipsoid to the minor = 4 : 3. Minor axis three times as large as
that of the inner spherical shell; pores of the latter, small, circular.
Two spines three-sided pyramidal, as long as the radius of the outer shell,
each as broad at its base as one mesh.

_Dimensions._--Longer axis of the ellipsoidal cortical shell 0.16, shorter
axis 0.12; pores 0.011, bars 0.003; diameter of the spherical medullary
shell 0.04; length of the polar spines 0.07; basal breadth 0.01.

_Habitat._--North Pacific, Station 253, depth 3125 fathoms.

2. _Lithatractus fragilis_, n. sp. (Pl. 16, fig. 3).

  _Stylosphæra fragilis_, Haeckel, 1881, Prodromus et Atlas, pl. xvi. fig.
  3.

Outer shell thin walled, smooth, without thorns or papillæ, with regular
network; the meshes circular, of equal size, eight to ten times as broad as
the thin bars; six to eight on the half equator. {320}Proportion of the
major axis of the ellipsoid to the minor = 5 : 4. Minor axis once and
one-third as broad as that of the ellipsoidal inner shell, the pores of
which are also circular, but of half the size. Two spines strong,
three-sided pyramidal, acute, as broad as a large mesh, as long as the
equatorial axis. The stout inner prolongations of these form the only
connection between the two shells.

_Dimensions._--Longer axis of the ellipsoidal cortical shell 0.12, shorter
axis 0.1; pores 0.02, bars 0.002; longer axes of the ellipsoidal medullary
shell 0.09, shorter axis 0.07; pores 0.01, bars 0.002; length of the polar
spines 0.1, basal breadth 0.002.

_Habitat._--Central area of the Pacific, Station 272, depth 2600 fathoms.

3. _Lithatractus leptostylus_, n. sp.

Outer shell thin walled, smooth, with regular, circular pores of equal
size, three to four times as broad as the thin bars; ten to twelve on the
half equator. Proportion of the major axis to the minor = 7 : 6. Minor axis
three times as large as that of the inner spherical shell; pores of the
latter half as large. Polar spines cylindrical, blunt, longer than the
major axis, scarcely half as broad as one larger pore.

_Dimensions._--Longer axis of the cortical shell 0.14, shorter axis 0.12;
pores 0.015 to 0.02, bars 0.004; diameter of the medullary shell 0.04;
length of the polar spines 0.15 to 0.2, its thickness 0.01.

_Habitat._--Central area of the Pacific, Stations 270 to 272, depth 2425 to
2925 fathoms.

4. _Lithatractus pachystylus_, n. sp.

Outer shell thick walled, smooth, with regular, circular pores of equal
size; twelve to fifteen on the half equator. Each pore is deep,
funnel-shaped, its outer aperture double the size of the inner, its breadth
about three times that of the high bars. Proportion of the major axis to
the minor = 6 : 5. Major axis double as long as the diameter of the
spherical medullary shell. Polar spines very thick and short, tetrahedral,
one-fourth as long and broad as the major axis.

_Dimensions._--Longer axis of the cortical shell 0.17, shorter axis 0.14;
pores 0.01, bars 0.003; diameter of the medullary shell 0.08; length and
thickness of the polar spines 0.04.

_Habitat._--Central area of the Pacific, Station 271, depth 2425 fathoms.

5. _Lithatractus convallaria_, n. sp.

Outer shell thick walled, smooth, with elegant regular network; the meshes
circular, six-lobed, rosette-like (of the same form as _Stauroxiphos
gladius_, Pl. 15, fig. 7), twice to three times as broad as the bars; six
to eight on the half equator. Proportion of the major axis of the ellipsoid
to the minor  = 4 : 3. Minor axis twice as long as the diameter of the
inner spherical shell, which has regular, simple, circular pores of half
the size. Polar spines short and thick, conical, only one-fourth to
one-sixth as long as the minor axis, and quite as thick.

_Dimensions._--Longer axis of the cortical shell 0.16, shorter axis 0.12;
pores 0.016, bars 0.006; diameter of the medullary shell 0.06; length of
the polar spines 0.02 to 0.03, basal thickness the same.

_Habitat._--Central area of the Pacific, Station 268, depth 2900 fathoms.

{321}Subgenus 2. _Lithatractylis_, Haeckel.

_Definition._--Network of the outer shell regular, with meshes of equal
size and similar form; surface thorny or papillose, covered with small
conical spines or tubercles.

6. _Lithatractus echiniscus_, n. sp.

Outer shell thorny, thin walled, with regular network; meshes circular,
with hexagonal frame, four to five times as broad as the thin bars;
eighteen to twenty on the half equator. From every corner between the three
meshes, where three hexagons unite, starts one short, straight, triangular
thorn (as in _Ellipsoxiphus elegans_, Pl. 14, fig. 7). Proportion of the
major axis of the ellipsoid to the minor = 4 : 3. Minor axis twice the
diameter of the inner spherical shell, the pores of which are half as
broad, circular. Polar spines three-sided pyramidal, about as long as the
minor axis, as broad at the base as one hexagonal frame.

_Dimensions._--Longer axis of the cortical shell 0.08, shorter axis = 0.06;
pores 0.004, bars 0.001; length of the polar spines 0.05, basal thickness
0.005; diameter of the inner shell 0.03.

_Habitat._--South Atlantic, off Tristan da Cunha, Station 334, surface.

7. _Lithatractus carduelis_, n. sp.

Outer shell thin walled, thorny, with regular network; meshes circular,
simple, four to six times as broad as the thin bars; ten to twelve on the
half equator. Between every three meshes is one short conical spine.
Proportion of the major axis to the minor = 6 : 5. Minor axis equals three
times the diameter of the inner spherical shell. Polar spines conical,
thick, half as long as the major axis, thicker at the base than one pore.
(This species differs from _Stylatractus carduus_ only by the simple
medullary shell.)

_Dimensions._--Longer axis of the ellipsoid 0.12 to 0.16, shorter axis 0.1
to 0.14; pores 0.02 to 0.03, bars 0.005; length of the polar spines 0.05 to
0.10, basal breadth 0.04; diameter of the medullary shell 0.03 to 0.04.

_Habitat._--Central area of the Pacific, Stations 268 to 274, depth 2350 to
2900 fathoms; also fossil in the rocks of Barbados.

8. _Lithatractus cirsium_, n. sp.

Outer shell thin walled, thorny, with regular network; pores circular,
simple, small, two to three times as broad as the thin bars; eighteen to
twenty-four on the half equator. Proportion of the major axis to the minor
= 4 : 3. Inner shell ellipsoidal, half as large as the outer. Polar spines
cylindrical, blunt, thin, very variable in length (one-fourth to
three-fourths of the major axis, not thicker than a mesh).

_Dimensions._--Longer axis of the ellipsoid 0.07 to 0.09, shorter axis 0.05
to 0.07; pores 0.005 to 0.006, bars 0.002; length of the polar spines 0.02
to 0.06, basal breadth 0.004; length of the inner shell 0.04, breadth 0.03.

_Habitat._--North Pacific, Station 244, surface.

{322}9. _Lithatractus rosetta_, n. sp.

Outer shell thick walled, thorny, with regular network; meshes circular,
funnel-shaped, its outer aperture elegant, rosette-like, with eight to ten
incisions (like _Stylosphæra calliope_, Pl. 16, fig. 6); eight to ten
meshes on the half equator, three to four times as broad as the bars.
Proportion of the longer axis to the shorter = 5 : 4. Shorter axis equals
three times the diameter of the inner spherical shell. Polar spines
three-sided pyramidal, about half as long as the shorter axis, as broad at
the base as a mesh.

_Dimensions._--Longer axis of the cortical shell 0.15, shorter 0.12; pores
0.02, bars 0.005; length of the polar spines 0.05, basal breadth 0.02;
diameter of the inner shell 0.04.

_Habitat._--South-eastern part of the Pacific, Station 302, depth 1450
fathoms.

Subgenus 3. _Lithatractona_, Haeckel.

_Definition._--Network of the outer shell irregular, with meshes of unequal
size or dissimilar form; surface smooth, without thorns or papillæ.

10. _Lithatractus conifer_, n. sp.

Outer shell thin walled, smooth, with irregular, roundish pores, two to
four times as broad as the thin bars; fifteen to twenty on the half
equator. Margin of the pores simple. Proportion of the major axis to the
minor = 3 : 2. Minor axis twice as large as the diameter of the inner
spherical shell, the pores of which are also irregular, roundish, but of
half the size. Polar spines conical, somewhat shorter than the main axis,
on the base two to three times as thick as a large pore.

_Dimensions._--Longer axis of the outer shell 0.15, shorter axis 0.1; pores
0.002 to 0.004, bars 0.001; diameter of the inner shell 0.05; length of the
polar spines 0.12, basal breadth 0.012.

_Habitat._--South Atlantic, Station 325, surface.

11. _Lithatractus lobatus_, n. sp.

Outer shell thick walled, smooth, with irregular, roundish pores, four to
eight times as broad as the bars; six to eight on the half equator. Margin
of the pores lobed, very irregular, bluntly dentate, by five to twenty
slight incisions. Proportion of the major axis to the minor very variable,
between 3 : 2 and 9 : 8. Diameter of the inner shell also variable, between
one-third and one-half of the outer; pores of the former scarcely half the
size of the latter, simple, roundish, or circular. The inner shell is at
some parts quite spherical, at other parts more or less ellipsoidal. Polar
spines conical, very variable in size and form, sometimes in the basal half
triangular; they are sometimes somewhat longer than the main axis, at other
times considerably shorter; their basal breadth is occasionally the same as
that of the largest pores, sometimes, however, scarcely half as large. This
deep-sea species is very common in the central area of the Tropical Pacific
(Stations 266 to 272), and occurs also fossil in the Barbados deposits. It
is interesting from its great variability, and sometimes constitutes a
transitional form to _Stylosphæra_.

{323}_Dimensions._--Longer axis of the outer shell 0.1 to 0.15, shorter
axis 0.05 to 0.12; pores 0.018 to 0.024, bars 0.002 to 0.004; diameter of
the inner shell 0.04 to 0.08; length of the polar spines 0.08 to 0.2, basal
thickness 0.01 to 0.02.

_Habitat._--Central area of the Pacific, common; Stations 266 to 272, depth
2425 to 2900 fathoms; also fossil in Barbados.

12. _Lithatractus jugatus_, n. sp. (Pl. 16, fig. 2).

  _Stylosphæra jugata_, Haeckel, 1881, Prodromus et Atlas (pl. xvi. fig.
  2).

Outer shell thick walled, smooth, or somewhat reticulated, with a peculiar,
irregular, double network. The pores are roundish, of very different sizes,
with double margin of the outer aperture, and so irregularly distributed in
polygonal groups that every group contains two to six pores immediately
touching each other; the groups are separated by broader bars. On the half
equator of the shell are about six to eight groups and twelve to eighteen
pores. Proportion of the longer axis of the ellipsoidal shell to the
shorter = 6 : 5 or 5 : 4. Inner ellipsoidal shell about half the size; its
pores are not easy to make out. Polar spines three-sided pyramidal, with
prominent edges, about half as long as the major axis, as broad at the base
as a group of pores. (Nearly allied to _Stylosphæra jugata_, p. 137.)

_Dimensions._--Longer axis of the cortical shell 0.12 to 0.16, shorter axis
0.1 to 0.13; pores 0.01 to 0.02; length of the polar spines 0.06 to 0.08,
basal breadth 0.03 to 0.4.

_Habitat._--Central area of the Pacific, Stations 266 to 272, depth 2425 to
2900 fathoms.

Subgenus 4. _Lithatractium_, Haeckel.

_Definition._--Network of the outer shell irregular, with meshes of unequal
size or dissimilar form; surface thorny or papillose, covered with small
conical spines or tubercles.

13. _Lithatractus conostylus_, n. sp.

Outer shell thorny, thin walled, with irregular network; pores roundish, of
unequal size, twice to four times as broad as the thin bars; sixteen to
twenty on the half equator. Proportion of the longer axis to the shorter =
5 : 4. Shorter axis twice the diameter of the inner spherical shell. Polar
spines conical, very stout, longer than the main axis, its base equals
one-third of the minor axis.

_Dimensions._--Major axis of the cortical shell 0.1, shorter axis 0.08;
pores 0.004 to 0.002, bars 0.001; diameter of the medullary shell 0.04;
polar spines--length 0.12, thickness 0.03.

_Habitat._--Central area of the Pacific, Station 271, depth 2425 fathoms.

14. _Lithatractus gamoporus_, n. sp.

Outer shell thorny, thick walled, with irregular network; pores roundish,
of unequal size, so irregularly distributed in polygonal groups that in
every group two to six pores (commonly three to four) are near together;
the groups are separated by broader bars. On the half equator {324}six to
eight groups and eighteen to twenty-four pores. Proportion of the longer
axis to the shorter = 6 : 5. Shorter axis equals twice the diameter of the
inner ellipsoidal shell. Polar spines three-sided pyramidal, about as long
as the equatorial axis, as broad at the base as a group of pores.

_Dimensions._--Major axis of the cortical shell 0.12, minor axis 0.1; pores
0.004 to 0.012, bars 0.003; length of the polar spines 0.1, basal breadth
0.03.

_Habitat._--Central area of the Pacific, Stations 271 to 274, depth 2350 to
2750 fathoms.

Genus 138. _Druppatractus_,[177] n. gen.

_Definition._--#Druppulida# with simple ellipsoidal cortical shell and
simple medullary shell, with two large opposite polar spines in the main
axis of different size or dissimilar form.

The genus _Druppatractus_ differs from its near relation _Lithatractus_ in
the differentiation of the two polar spines, which are different in size or
form, often to a very considerable degree. It has therefore the same
relation to the latter that _Ellipsoxiphus_ bears to _Ellipsostylus_.

Subgenus 1. _Druppatractara_, Haeckel.

_Definition._--Network of the cortical shell regular or subregular, with
meshes of nearly equal size and similar form; surface smooth, without
thorns or papillæ.

1. _Druppatractus ichthydium_, n. sp.

Cortical shell thin walled, with smooth surface and regular network.
Proportion of the major axis to the minor = 3 : 2.  Pores circular,
hexagonally framed, twice as broad as the bars; seven to eight on the half
equator (as in _Xiphostylus alcedo_, Pl. 13, fig. 4). Medullary shell
spherical, one-third as broad as the cortical shell. Polar spines straight,
three-sided pyramidal, as broad at the base as one mesh; the longer equals
the main axis of the cortical shell, the shorter only its half.

_Dimensions._--Major axis of the ellipsoidal cortical shell 0.18, minor
axis 0.12; pores 0.01, bars 0.005; diameter of the medullary shell 0.04;
length of the major polar spine 0.16 to 0.2, of the minor 0.01 to 0.12,
basal breadth 0.01.

_Habitat._--Mediterranean (Corfu), surface, Haeckel.

2. _Druppatractus hippocampus_, n. sp. (Pl. 16, figs. 10, 11).

  _Stylosphæra hippocampus_, Haeckel, 1881, Atlas, pl. xvi. figs. 10, 11.

Cortical shell thick walled, with smooth surface and regular network.
Proportion of both axes = 7 : 6. Pores circular, hexagonally lobed, three
times as broad as the bars; nine to ten on the half {325}equator. Medullary
shell ellipsoidal, nearly half as large as the cortical. Larger polar spine
horn-like curved, as long as the main axis, smaller scarcely half as long,
pommel-shaped.

_Dimensions._--Major axis 0.09, minor 0.075; pores 0.01, bars 0.003; axes
of the medullary shell 0.04 and 0.03; length of the larger polar spine 0.06
to 0.09, of the smaller 0.04, basal breadth 0.02.

_Habitat._--Pacific, central area, Stations 270 to 272, surface.

3. _Druppatractus belone_, n. sp.

Cortical shell thin walled, with smooth surface and regular network.
Proportion of both axes = 4 : 3. Pores circular, twice as broad as the
bars; ten to twelve on the half equator. Medullary shell spherical,
one-third as broad as the cortical shell. Polar spines strong, straight,
cylindrical, with conical apex, as broad at the base as two pores; the
larger once and a half to twice as long as the main axis, the smaller only
one-third to one-fourth as long.

_Dimensions._--Major axis 0.1 to 0.12, minor 0.08 to 0.09; pores 0.008,
bars 0.004; diameter of the medullary shell 0.03; length of the larger
polar spine 0.15 to 0.2, of the minor 0.04 to 0.05, basal thickness of them
0.02.

_Habitat._--Cosmopolitan; Atlantic, Indian, and Pacific, surface.

4. _Druppatractus testudo_, Haeckel.

  _Stylosphæra testudo_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 299, Taf. viii. fig. 16.

Cortical shell thick walled, spindle-shaped, with smooth surface and
regular network. Proportion of the two axes = 3 : 2. Pores circular, five
times as broad as the bars; only six to seven on the half equator.
Medullary shell ellipsoidal, about one-third as large as the cortical
shell. Polar spines strong, short, three-sided pyramidal; the larger as
long as half the transverse axis, the smaller only one-fourth as long.

_Dimensions._--Major axis 0.12, minor 0.8; pores 0.015, bars 0.003; axes of
the medullary shell 0.04 and 0.03; length of the larger polar spine 0.04,
of the smaller 0.02, basal thickness 0.01.

_Habitat._--Pacific, Philippine and Californian Sea (Ehrenberg), Stations
244, 266, 289, &c., depth 2550 to 2900 fathoms.

Subgenus 2. _Druppatractylis_, Haeckel.

_Definition._--Network of the cortical shell regular or subregular, with
meshes of nearly equal size and similar form; surface thorny or papillose,
covered with small conical spines or tubercles.

5. _Druppatractus accipenser_, n. sp.

Cortical shell thick walled, thorny, with regular network. Proportion of
the two axes = 6 : 5. Pores circular, each with a six-lobed outer opening,
funnel-shaped, twice as broad as the bars; nine {326}to ten on the half
equator. Medullary shell spherical, one-third as broad as the cortical
shell. Polar spines very strong, three-sided pyramidal, as broad at the
base as three pores; the larger about as long as the main axis, the smaller
only one-third as long.

_Dimensions._--Major axis 0.12, minor 0.1; pores 0.01, bars 0.005;
medullary shell 0.035; length of the larger polar spine 0.11, of the
smaller 0.04, basal breadth 0.03.

_Habitat._--Indian Ocean, Madagascar, surface, Rabbe.

6. _Druppatractus ostracion_, n. sp. (Pl. 16, figs. 8, 9).

Cortical shell thick walled, thorny, with regular network. Proportion of
the two axes = 4 : 3. Pores circular, hexagonally framed, three to four
times as broad as the crested bars; from every corner of the hexagon
(between three meshes) arises a short papilla; the bottom of every
funnel-like mesh is closed by a very thin plate with three regular,
circular pores (occasionally four), sometimes confluent, at other times
separate. Medullary shell (fig. 9) half as large as the cortical,
ellipsoidal and papillate, with regular, circular pores. Polar spines very
strong, three-sided prismatic, often somewhat irregular, with short apex;
the larger once to twice as long as the main axis, the smaller scarcely
half as long.

_Dimensions._--Major axis 0.16, minor 0.12; pores 0.02 (porules at their
base 0.01), bars 0.006; axes of the medullary shell 0.07 and 0.06, its
pores 0.01, bars 0.003; length of the larger polar spine 0.15 to 0.3, of
the smaller 0.07 to 0.09, basal thickness 0.03.

_Habitat._--Pacific, central area, Station 265, depth 2900 fathoms.

7. _Druppatractus coronatus_, Haeckel.

  _Stylosphæra coronata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 84, Taf. xxv. fig. 4.

Cortical shell thick walled, thorny, with regular network. Proportion of
the two axes = 5 : 4. Pores circular, simple, twice as broad as the bars;
eight to ten on the half equator. Medullary shell circular, one-third as
broad as the cortical shell. Polar spines furrowed and angular; the longer
and thinner pyramidal about as long as the main axis, the shorter and
thicker scarcely half as long, thickened towards the short conical apex.

_Dimensions._--Major axis 0.08 to 0.1, minor 0.06 to 0.08; pores 0.01, bars
0.005; diameter of the medullary shell 0.03; length of the large polar
spine 0.08 to 0.12, of the shorter 0.04 to 0.05.

_Habitat._--Fossil in the Tertiary rocks of Barbados; also living in the
depths of the Pacific, central area, Stations 265 to 268, depth 2700 to
2900 fathoms.

Subgenus 3. _Druppatractona_, Haeckel.

_Definition._--Network of the cortical shell irregular, with meshes of
unequal size or dissimilar form; surface smooth, without thorns or papillæ.

{327}8. _Druppatractus lævis_, Haeckel.

  _Stylosphæra lævis_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 84, Taf. xxv. fig. 6.

Cortical shell thin walled, smooth, with irregular network. Proportion of
the two axes = 3 : 2. Pores roundish or subcircular, of different size,
one-half to twice as broad as the bars; eight to ten on the half equator.
Medullary shell ellipsoidal, one-third as large as the cortical shell.
Polar spines conical, the larger and thinner nearly as long as the main
axis, the shorter and thicker scarcely one-third as long.

_Dimensions._--Major axis 0.07 to 0.1, minor 0.05 to 0.07; pores and bars
0.005 to 0.01; axes of the medullary shell 0.03 and 0.02; length of the
major polar spine 0.06 to 0.09, of the shorter 0.03 to 0.04.

_Habitat._--Cosmopolitan; Atlantic, Indian, Pacific, surface.

9. _Druppatractus xiphias_, n. sp.

Cortical shell thick walled, smooth, with irregular network. Proportion of
the two axes = 6 : 5. Pores funnel-shaped, composed of two to four
confluent smaller porules, twice to four times as broad as the bars; ten to
twelve on the half equator. Medullary shell spherical, half as broad. Polar
spines three-sided pyramidal, the larger about as long as the main axis,
the shorter one-third to one-half as long.

_Dimensions._--Major axis 0.12, minor 0.1; pores 0.012 to 0.018, bars
0.004; diameter of the medullary shell 0.05; length of the major polar
spine 0.1, of the minor 0.03 to 0.05.

_Habitat._--Pacific, central area, Station 268, depth 2900 fathoms.

Subgenus 4. _Druppatractium_, Haeckel.

_Definition._--Network of the cortical shell irregular, with meshes of
unequal size or dissimilar form; surface thorny or papillose, covered with
small spines or tubercles.

10. _Druppatractus diodon_, n. sp.

Cortical shell thin walled, thorny, with irregular network. Proportion of
the two axes = 5 : 4. Pores simple, irregular, roundish, twice to four
times as broad as the bars; eight to ten on the half equator. Medullary
shell spherical, half as broad. Polar spines conical, more or less curved;
the major longer than the main axis, the minor scarcely half as long.
(Resembles _Sphærostylus ophidium_, Pl. 16, figs. 14, 15, but differs from
it in the prolongation of the main axis.)

_Dimensions._--Major axis 0.15, minor 0.12; pores 0.01 to 0.02, bars 0.005;
diameter of the medullary shell 0.06; length of the larger polar spine 0.12
to 0.18, of the shorter 0.06 to 0.08, basal thickness 0.003.

_Habitat._--Pacific, central area, Station 274, surface.

{328}11. _Druppatractus pisciculus_, n. sp.

Cortical shell thick walled, spiny, with irregular network. Proportion of
the two axes = 3 : 2. Pores irregular, roundish, lobed, or composed of
three to five confluent porules, twice to six times as broad as the bars;
six to eight on the half equator. (Similar to _Ellipsoxiphus atractus_, Pl.
14, fig. 1.) Medullary shell ellipsoidal, nearly half as large as the
cortical shell. Polar spines three-sided pyramidal, the major longer than
the main axis, the minor scarcely one-third to one-fourth as long.

_Dimensions._--Major axis 0.18, minor 0.12; pores 0.01 to 0.03, bars 0.004;
axes of the medullary shell 0.08 and 0.05; length of the major polar spine
0.2, of the minor 0.05, basal breadth 0.02.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

Genus 139. _Stylatractus_,[178] n. gen.

_Definition._--#Druppulida# with simple ellipsoidal cortical shell and
double medullary shell, in the main axis with two large opposite polar
spines of equal size and similar form.

The genus _Stylatractus_ differs from _Lithatractus_ in the double
medullary shell, from _Amphisphæra_ in the ellipsoidal form of the cortical
shell. As in these two genera, both opposite polar spines have the same
shape and size.

Subgenus 1. _Stylatractara_, Haeckel.

_Definition._--Network of the cortical shell regular or subregular, with
meshes of nearly equal size and similar form; surface smooth, without
thorns or papillæ.

1. _Stylatractus neptunus_, n. sp. (Pl. 17, fig. 6).

  _Amphistylus neptunus_, Haeckel, 1878, Atlas, pl. xvii. fig. 6.

Cortical shell thick walled, smooth, with subregular, circular, polygonally
framed pores, quite as broad as the bars; ten to twelve on the half
equator. Polar spines three-sided pyramidal, about as long as the half main
axis, three times as broad at the base as the pores. (Much resembles
_Amphisphæra neptunus_, p. 142, but differs from it by the prolongation of
the main axis, which equals one and a half or one and a fourth the
equatorial axis, and by the somewhat irregular formation of the cortical
hexagonal network. Sometimes also, as in the figured specimen, the length
of both polar spines is somewhat different.)

_Dimensions._--Major axis of the cortical shell 0.15, minor axis 0.12;
pores and bars 0.007; main axes of both ellipsoidal medullary shells 0.08
and 0.05; length of the polar spines 0.08 to 0.1, basal breadth 0.02.

_Habitat._--Pacific, central area, Stations 266 to 268, depth 2700 to 2900
fathoms.

{329}2. _Stylatractus fusiformis_, n. sp.

Cortical shell thick walled, smooth, with regular, simple, circular pores,
quite as broad as the bars; fourteen to sixteen on the half equator. Polar
spines three-sided pyramidal, half as long as the main axis, as broad at
the base as the inner medullary shell. (Resembles very nearly _Xiphatractus
armadillo_, Pl. 17, fig. 11, but differs in the regular form and equal
length of the polar spines.)

_Dimensions._--Major axis 0.17, minor axis 0.13; pores and bars 0.007; main
axes of both ellipsoidal medullary shells 0.09 and 0.05; length of the
polar spines 0.08, basal breadth 0.04.

_Habitat._--Cosmopolitan; Atlantic, Indian, Pacific, at various depths.

3. _Stylatractus compactus_, n. sp. (Pl. 17, fig. 4).

Cortical shell thick walled, smooth, with subregular, circular,
double-contoured pores, smaller than the bars; sixteen to eighteen on the
half equator. The thickness of the shell-wall equals the radius of the
inner medullary shell. Polar spines short, three-sided pyramidal; their
length and basal thickness variable, but commonly equal to the diameter of
the inner medullary shell.

_Dimensions._--Major axis 0.16, minor axis 0.13; pores 0.007, bars 0.01;
main axes of both ellipsoidal medullary shells 0.09 and 0.04; length and
basal breadth of the polar spines 0.04 to 0.05.

_Habitat._--Pacific, central area, Stations 270 to 272, depth 2425 to 2925
fathoms.

Subgenus 2. _Stylatractylis_, Haeckel.

_Definition._--Network of the outer shell regular, with meshes of equal
size and similar form; surface thorny or papillose, covered with small
spinules or tubercles.

4. _Stylatractus giganteus_, n. sp. (Pl. 17, fig. 1).

  _Amphistylus giganteus_, Haeckel, 1879, Atlas (pl. xvii. fig. 1).

Cortical shell papillose, very thick walled, with regular network; pores
circular, with double margin, about twice as broad as the bars; ten to
twelve on the half equator. The cortical shell is connected with the outer
medullary shell by numerous strong beams, and the inner prolongations of
both polar spines are much stronger. The circular pores of the outer
medullary shell are three times as large as those of the inner, and equal
to those of the cortical shell, but the bars are much thinner. Polar spines
very strong, three-sided pyramidal, with spirally contorted edges, as long
as the main axis, as broad at the base as the inner medullary shell.

_Dimensions._--Major axis of the cortical shell 0.3, minor axis 0.22; pores
0.02, bars 0.01; main axes of the ellipsoidal medullary shells 0.14 and
0.07; length of the polar spines 0.3, basal thickness 0.06.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.

{330}5. _Stylatractus carduus_, Haeckel.

  _Stylosphæra carduus_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 84, Taf. xxv. fig. 7.

Cortical shell thin walled, spiny, with regular, circular pores, five times
as broad as the bars; ten to twelve on the half equator. Polar spines
conical, half as long as the main axis, at the base broader than the pores.
(The cortical shell is ellipsoidal as well as both medullary shells; the
figure of Ehrenberg, as is generally the case, is more correct than his
description. This interesting species occurs in the Barbados rocks, with
double as well as with simple medullary shell, and may in the latter case
be distinguished as _Lithatractus carduelis_.)

_Dimensions._--Major axis of the cortical shell 0.12 to 0.16, minor 0.1 to
0.14; pores 0.01 to 0.02, bars 0.002 to 0.005; main axes of the ellipsoidal
medullary shells 0.05 and 0.03; length of the polar spines 0.06, basal
breadth 0.02.

_Habitat._--Fossil in the Tertiary rocks of Barbados.

Subgenus 3. _Stylatractona_, Haeckel.

_Definition._--Network of the outer shell irregular, with meshes of
different size or form; surface smooth, without thorns or papillæ.

6. _Stylatractus variabilis_, n. sp.

Cortical shell thin walled, smooth, with irregular, roundish pores, twice
to six times as broad as the bars; twelve to sixteen on the half equator.
Polar spines conical, about half as long as the main axis, and as broad at
the base as the inner medullary shell. (The size and form of the pores and
of the polar spines in this species are very variable, so that the
proportions given are to be understood as averages.)

_Dimensions._--Major axis 0.13, minor axis 0.11; pores 0.004 to 0.012, bars
0.002; main axes of the ellipsoidal medullary shells 0.07 and 0.04; length
of the polar spines 0.06, basal breadth 0.03.

_Habitat._--Pacific, central area. Stations 272 to 274, depth 2350 to 2750
fathoms.

7. _Stylatractus sethoporus_, n. sp. (Pl. 17, figs. 2, 3).

Cortical shell thick walled, smooth, with large irregular, roundish pores,
twice to four times as broad as the bars; seven to eight on the half
equator. At the bottom of each pore a thin lamella of silex, perforated by
four to six irregular, roundish, double-contoured porules. Medullary shells
resemble those of _Stylatractus giganteus_. Polar spines three-sided
pyramidal; their length and basal thickness scarcely equal the diameter of
the inner medullary shell.

_Dimensions._--Major axis 0.15, minor axis 0.13; pores 0.02, bars 0.005,
porules 0.01; length of the polar spines 0.04.

_Habitat._--Pacific, central area, Station 272, depth 2600 fathoms.

{331}Subgenus 4. _Stylatractium_, Haeckel.

_Definition._--Network of the outer shell irregular, with meshes of
different size and form; surface thorny or papillose, covered with small
spinules or tubercles.

8. _Stylatractus papillosus_, n. sp.

Cortical shell thin walled, with papillose surface, and irregular, simple,
roundish pores, ten to sixteen on the half equator, twice to three times as
broad as the bars. Conical papillæ of the surface irregularly scattered.
Polar spines conical, about as long as the main axis, at the base half as
broad as the inner medullary shell.

_Dimensions._--Major axis 0.12, minor 0.1; pores 0.006 to 0.01, bars 0.003;
main axes of the medullary shells 0.09 and 0.06; length of the polar spines
0.13, basal breadth 0.04.

_Habitat._--Indian Ocean, surface (between Socotra and Ceylon), Haeckel.

9. _Stylatractus disetanius_, n. sp.

Cortical shell thin walled, with spiny surface, and irregular, roundish
pores, eight to ten on the half equator, twice to three times as broad as
the bars. Every pore is divided by thinner bars into four to six small
roundish porules. Polar spines three-sided pyramidal, nearly as long as the
main axis, as broad at the base as the inner medullary shell. (Resembles
_Xiphatractus glyptodon_, Pl. 17, figs. 9, 10, but differs from it by the
irregular network and the equal size of both polar spines.)

_Dimensions._--Major axis 0.14, minor 0.1; pores 0.02, bars 0.008, porules
0.007; main axes of the two medullary shells 0.08 and 0.05; length of the
polar spines 0.13, basal breadth 0.04.

_Habitat._--South Pacific, near New Zealand, Station 169, surface.

Genus 140. _Xiphatractus_,[179] n. gen.

_Definition._--#Druppulida# with a simple ellipsoidal cortical shell and
double medullary shell, in the main axis with two large opposite polar
spines of different size or form.

The genus _Xiphatractus_ differs from the nearly related _Stylatractus_ in
the differentiation of two polar spines (in the same manner as
_Druppatractus_ differs from _Lithatractus_). From the spherical
_Amphistylus_ it differs in the ellipsoidal form of the cortical shell.

Subgenus 1. _Xiphatractara_, Haeckel.

_Definition._--Network of the cortical shell regular or subregular, with
meshes of nearly equal size and similar form; surface smooth, without
thorns or papillæ.

{332}1. _Xiphatractus armadillo_, n. sp. (Pl. 17, fig. 11).

Cortical shell thick walled, smooth, with regular, circular pores, about as
broad as the bars; fifteen to sixteen on the half equator. Polar spines
three-sided pyramidal, with thick, prominent edges, of irregular form; the
longer about as long as the main axis, the shorter scarcely one-third as
long; their basal breadth equals the diameter of the inner medullary shell.

_Dimensions._--Major axis of the cortical shell 0.13, minor axis 0.1,
thickness of its wall 0.01; pores and bars 0.005; main axes of the two
medullary shells 0.07 and 0.03; length of the major polar spine 0.12, of
the minor 0.04, basal thickness 0.04.

_Habitat._--Pacific, central area, Station 272, depth 2600 fathoms.

2. _Xiphatractus euphractus_, n. sp.

Cortical shell thick walled, smooth, with regular, circular pores, twice as
broad as the bars; eight to nine on the half equator. Each pore has six to
nine excisions (commonly eight), elegantly lobed, flower-like (as in
_Xiphostylus phasianus_, Pl. 13, fig. 9). Polar spines strong, angulate;
the major pyramidal, longer than the main axis, the shorter elegantly
pommel-like, scarcely one-third as long.

_Dimensions._--Major axis 0.15, minor 0.12; pores 0.014, bars 0.007; main
axes of the two medullary shells 0.09 and 0.05; length of the larger polar
spine 0.16, of the shorter 0.05, greatest thickness 0.03.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

Subgenus 2. _Xiphatractylis_, Haeckel.

_Definition._--Network of the cortical shell regular or subregular, with
meshes of nearly equal size and similar form; surface thorny or papillose.

3. _Xiphatractus spinulosus_, Haeckel.

  _Stylosphæra spinulosa_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 84, Taf. xxv. fig. 8.

Cortical shell thin walled, with spiny surface, and large, regular,
circular pores, four times as broad as the bars; seven to eight on the half
equator. Spines between the pores of the same size, conical. Polar spines
also conical, but much larger; the major about as long as the main axis,
the minor scarcely half as long; their basal thickness equals the largest
pores.

_Dimensions._--Major axis 0.1, minor 0.08; pores 0.012, bars 0.003;
diameter of the spherical medullary shells 0.06 and 0.03; length of the
major polar spine 0.09, of the minor 0.04, basal thickness 0.02.

_Habitat._--Fossil in the Tertiary rocks of Barbados.

{333}4. _Xiphatractus sulcatus_, Haeckel.

  _Stylosphæra sulcata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 84, Taf. xxiv, fig. 6.

Cortical shell thick walled, with thorny surface, and regular, circular
pores, quite as broad as the bars; nine to ten on the half equator. Polar
spines cylindrical, with longitudinal basal furrows and conical apex, three
times as broad as the pores; the larger about as long as the main axis, the
shorter only one-half or two-thirds as long.

_Dimensions._--Major axis 0.01, minor 0.08; pores and bars 0.007; main axes
of the two medullary shells 0.08 and 0.04; length of the major polar spine
0.1, of the minor 0.06, breadth of them 0.02.

_Habitat._--Fossil in the Barbados deposits.

5. _Xiphatractus dasypus_, n. sp.

Cortical shell thick walled, with spiny surface, and regular, elegant
network; pores circular, hexagonally framed, about as broad as the bars;
from every corner of the network (between three pores) arises a short
bristle-like spine. Polar spines three-sided prismatic, as broad as one
hexagon; the major once to twice as long as the main axis, the minor only
one-half to one-fourth as long. (The cortical shell much resembles
_Ellipsoxiphus elegans_, Pl. 14, fig. 7.)

_Dimensions._--Major axis 0.15, minor 0.13; pores and bars 0.01; main axes
of the two medullary shells 0.1 and 0.06; length of the major polar spine
0.1 to 0.3, of the minor 0.05 to 0.1, thickness 0.01.

_Habitat._--Tropical Western Pacific, Station 222, surface.

Subgenus 3. _Xiphatractona_, Haeckel.

_Definition._--Network of the cortical shell irregular, with meshes of
different size or form; surface smooth, without thorns or papillæ.

6. _Xiphatractus chlamydophorus_, n. sp.

Cortical shell thin walled, smooth, with irregular, roundish pores, twice
to four times as broad as the bars; eight to twelve on the half equator.
Polar spines angular, irregularly curved or contorted; the larger once to
twice as long as the main axis, the shorter and thicker pommel-shaped, only
one-third to one-half as long; their basal breadth equals two pores.

_Dimensions._--Major axis 0.14, minor 0.1; pores 0.006 to 0.012, bars
0.003; main axis of the two ellipsoidal medullary shells 0.09 and 0.04;
length of the major polar spine 0.1 to 0.2, of the minor 0.05 to 0.08,
breadth 0.02.

_Habitat._--Cosmopolitan; Atlantic, Pacific, many Stations, surface.

{334}Subgenus 4. _Xiphatractium_, Haeckel.

_Definition._--Network of the cortical shell irregular, with meshes of
unequal size or dissimilar form; surface thorny or papillose.

7. _Xiphatractus radiosus_, Haeckel.

  _Stylosphæra radiosa_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 84, Taf. xxiv. fig. 5.

Cortical shell very thick walled, with thorny surface, and irregular,
roundish pores, once to three times as broad as the bars; nine and ten on
the half equator. Polar spines conical, on the base about as broad as the
largest pores; the larger as long as the main axis, the smaller scarcely
one-fourth as long. (The radial striation, figured by Ehrenberg and applied
to the name of this species, is produced by the contours of the
funnel-shaped pores in the thick walls seen in optical section; the
ellipsoidal cortical shell is double.)

_Dimensions._--Major axis 0.13, minor 0.09; pores 0.003 to 0.01, bars
0.003; main axes of the two medullary shells 0.05 and 0.03; length of the
major polar spine 0.12, of the minor 0.03, basal breadth 0.01.

_Habitat._--Fossil in the Tertiary rocks of Barbados.

8. _Xiphatractus glyptodon_, n. sp. (Pl. 17, figs. 9, 10).

Cortical shell thick walled, covered with radial spines of the size of the
pores; on the half equator eight to ten irregular or subregular roundish
pores, twice to four times as broad as the bars. In the bottom of each pore
a thin lamella of silex, perforated by four to six smaller roundish pores.
Both medullary shells (fig. 10) spherical, with smaller, regular, circular
pores. Larger polar spine three-sided pyramidal, in length equals the main
axis; shorter spine only half as long, but twice as thick, of elegant
pommel-form (fig. 9), with nine prominent edges.

_Dimensions._--Major axis 0.12, minor, 0.1; pores and spines 0.01 to 0.02,
bars and porules 0.005; diameter of the two medullary shells 0.05 and 0.02;
length of the major polar spine 0.1, of the minor 0.06, greatest thickness
0.04.

_Habitat._--Pacific, central area, Station 263, surface.

Genus 141. _Cromyatractus_,[180] n. gen.

_Definition._--#Druppulida# with four or more concentric shells (two
medullary shells and two or more cortical shells), in the main axis with
two large opposite polar spines of equal size and similar form.

The genus _Cromyatractus_ is very nearly allied to all the foregoing
genera, which bear two equal spines opposite to one another on the poles of
the main axis; it differs {335}from them in the multiplication of the
cortical shell, and may be considered as the most highly developed form of
this amphistylous series, which proceeds from _Ellipsoxiphus_ to
_Lithatractus_ and _Stylatractus_.

Subgenus 1. _Cromyatractium_, Haeckel.

_Definition._--Shell composed of two medullary shells and two cortical
shells.

1. _Cromyatractus tetraphractus_, n. sp. (Pl. 15, fig. 2).

  _Stylocromium tetraphractum_, Haeckel, 1879, Atlas (pl. xv. fig. 2).

Proportion of the main axes of the four concentric shells about =
1 : 3 : 5 : 7. Network of all four shells nearly of the same structure,
subregular, with circular pores of equal size (in one and the same shell).
The absolute size of the pores increases gradually from the innermost to
the outermost shell. The bars between the pores are smaller and quite
smooth. Surface of the outermost shell smooth. Polar spines cylindrical,
with conical apex, of variable length, nearly as broad as the innermost
shell.

_Dimensions._--Main axes of the four shells--(A) inner medullary shell
0.03, (B) outer medullary shell 0.08, (C) inner cortical shell 0.15, (D)
outer cortical shell 0.2; equatorial axes of them--(A) 0.025, (B) 0.06, (C)
0.12, (D) 0.15; pores of (A) 0.004, (B) 0.007, (C) 0.01, (D) 0.013, bars
0.002 to 0.004; length of the polar spines 0.1 to 0.3 (and more), breadth
0.015.

_Habitat._--Antarctic (Indian) Ocean, Station 157, depth 1950 fathoms.

2. _Cromyatractus tetralepas_, n. sp.

Proportion of the main axes of the four concentric shells about =
1 : 2 : 4 : 6. Network of the two medullary shells regular, with small
circular pores, little larger than the bars. Network of the two cortical
shells irregular, with much larger polygonal pores, three to nine times as
broad as the thin bars. (Somewhat similar to _Cromyatractus ceparius_, Pl.
15, fig. 4.) Surface of the outermost shell smooth or a little thorny.
Polar spines cylindrical, very large, twice to three times as long as the
main axis of the outermost shell, about as broad as the innermost shell,
with conical apex; smooth or a little thorny.

_Dimensions._--Main axes of the four shells--(A) 0.03, (B) 0.05, (C) 0.13,
(D) 0.18; equatorial axes of them--(A) 0.2, (B) 0.45, (C) 0.11, (D) 0.14;
pores of the two medullary shells 0.004 and 0.006, of both cortical shells
0.01 to 0.03, bars 0.003.

_Habitat._--Indian Ocean, Zanzibar, Pullen, 2200 fathoms.

3. _Cromyatractus tetracelyphus_, n. sp. (Pl. 15, figs. 1, 1_a_).

Proportion of the main axes of the four concentric shells about =
1 : 3 : 10 : 11. Network of the two spherical medullary shells (fig. 1_a_)
regular, with small circular pores, twice as broad as {336}the bars.
Network of the inner cortical shell regular with circular,
hexagonally-framed pores, twice as broad as the bars. From every corner of
the hexagons (between three pores) arises a very thin, hair-like, short
radial spinule. These spinules communicate with one another by tangential
branches (at equal distances from the inner cortical shell), and form
thereby an outer, delicate cortical network, with large polygonal meshes
and very thin bars. Polar spines very strong, pyramidal, with prominent
edges, as long as the main radius of the cortical shell, and half as broad
at the base.

_Dimensions._--Main axes of the four shells--(A) 0.02, (B) 0.06, (C) 0.2,
(D) 0.22; equatorial axes of them--(A) 0.02, (B) 0.06, (C) 0.13, (D) 0.15;
pores of the four shells--(A) 0.002, (B) 0.004, (C) 0.008, (D) 0.02; bars
0.001 to 0.003; length of the polar spines 0.1, basal breadth 0.05.

_Habitat._--South Atlantic, Station 335, depth 1425 fathoms.

Subgenus 2. _Caryatractus_, Haeckel.

_Definition._--Shell composed of two medullary shells and three or more
cortical shells.

4. _Cromyatractus cepicius_, n. sp. (Pl. 15, fig. 3).

  _Caryostylus cepicius_, Haeckel, 1879, Atlas (pl. xv. fig. 3).

  _Caryodoras cepicius_, Haeckel, 1881, Prodromus, p. 454.

Proportion of the main axes of the five concentric shells about =
1 : 2 : 5 : 7 : 8. Network of both spherical medullary shells regular, with
small circular pores, about as broad as the bars. Network of the three
ellipsoidal cortical shells irregular, with large polygonal meshes, five to
ten times as broad as the thin bars. Surface of the outermost shell smooth.
Polar spines cylindrical, thorny, about as thick as the innermost shell and
as long as the outermost shell, against the apex with a spindle-like
intumescence, formed by delicate spongy framework (fig. 3).

_Dimensions._--Main axes of the five concentric shells--(A) 0.03, (B) 0.05,
(C) 0.16, (D) 0.2, (E) 0.25; equatorial axes of them--(A) 0.03, (B) 0.05,
(C) 0.12, (D) 0.16, (E) 0.2; pores of the two medullary shells 0.002 to
0.004, of the three cortical shells 0.02 to 0.04, bars 0.002; length of the
polar spines 0.3, breadth 0.03.

_Habitat._--Pacific, central area, Station 268, depth 2900 fathoms.

5. _Cromyatractus ceparius_, n. sp. (Pl. 15, fig. 4).

  _Caryostylus ceparius_, Haeckel, 1881, Prodromus et Atlas (pl. xv. fig.
  4).

Proportion of the main axes of the six concentric shells about =
1 : 2 : 7 : 10 : 13 : 18. Network of the three inner shells regular, with
small, circular pores, which are about as broad as the bars and in the
third shell hexagonally framed.  Network of the three outer shells
irregular, with large polygonal meshes, six to twelve times as broad as the
bars. Surface smooth. Polar spines strong, spindle-shaped, thorny, outside
of the sixth shell about as long as inside of it; broader than {337}the
innermost shell; the thorns of their outer free part (arising at equal
distances) represent perhaps the beginnings of three to four further
shells.

_Dimensions._--Main axes of the six concentric shells--(A) 0.02, (B) 0.05,
(C) 0.14, (D) 0.2, (E) 0.26, (F) 0.37; equatorial axes--(A) 0.02, (B) 0.05,
(C) 0.09, (D) 0.15, (E) 0.21, (F) 0.3; pores of the three inner shells
0.003 to 0.006, of the three outer shells 0.02 to 0.04, bars 0.003 to
0.005; length of the polar spines, from the base of the innermost shell to
the apex, 0.35, greatest breadth 0.03.

_Habitat._--South Pacific, Station 285, depth 2375 fathoms.

Genus 142. _Pipetta_,[181] n. gen.

_Definition._--#Druppulida# with simple ellipsoidal cortical shell and
simple medullary shell, with two hollow fenestrated tubes opposite on both
poles of the main axis.

The genus _Pipetta_ differs from _Pipettella_ (p. 304) in the possession of
an inner (medullary) shell; it exhibits the same tubular prolongations of
the cortical shell at both poles of the main axis.

1. _Pipetta fusus_, n. sp. (Pl. 39, figs. 8, 8_a_).

Cortical shell spindle-shaped, the middle ellipsoidal part gently passing
over on both poles into the conical tubes, which attain about the same
length. Network regular, with circular, hexagonally-framed pores, twice as
broad as the bars, sixteen to eighteen on the half equator. In the middle
part of the shell the pores arise from their hexagonal bases in the form of
short conical funnels; on both tubes they are much smaller and simple,
without frame. Medullary shell (fig. 8_a_) spherical, scarcely one-third as
broad as the cortical, with regular, circular pores, twice as broad as the
bars, eight to nine on the half equator. The two shells are connected only
by two opposite beams, lying in the equatorial axis and ramified at the
distal insertion (fig. 8_a_).

_Dimensions._--Middle ellipsoidal part of the cortical shell 0.13 to 0.15;
polar tubes 0.15 long, 0.06 broad at the base; pores of the former 0.01,
bars 0.005; pores of the tubes 0.06, bars 0.003. Medullary shell 0.04,
pores 0.004, bars 0.002.

_Habitat._--Pacific, central area, Station 268, depth 2900 fathoms.

2. _Pipetta tuba_, n. sp. (Pl. 39, fig. 7).

Cortical shell nearly spherical in the middle part, which is sharply
separated at both poles from the long, nearly cylindrical tubes; these are
longer than the main axis, at the distal end open (always broken off).
Network regular, with circular, hexagonally-framed pores, of the same
breadth as the bars, eighteen to twenty on the half equator. The pores of
the polar tubes are of the same shape, only much smaller, and arranged in
sixteen to eighteen longitudinal rows. Medullary shell {338}spherical,
about one-third as broad as the cortical, with simple circular pores. The
connection between the two shells is only made by two simple opposite
beams, lying in the equatorial axis.

_Dimensions._--Middle spheroidal part of the cortical shell 0.14 to 0.16;
polar tubes 0.15 to 0.2 or longer, 0.03 broad; pores and bars of the former
0.007, of the latter 0.003. Medullary shell 0.04, pores 0.006, bars 0.003.

_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.

3. _Pipetta salpinx_, n. sp.

Cortical shell ellipsoidal, sharply separated from the cylindrical polar
tubes, which reach about the same length (or more). Network regular, with
circular pores, three times as broad as the bars, without hexagonal frames,
fourteen to fifteen on the half equator. Pores of the polar tubes smaller,
arranged in eight to ten longitudinal rows. Medullary shell spherical,
one-fourth as broad as the cortical, connected with it by a circle of four
to six radial beams, lying in the equatorial plane. Differs from
_Pipettella prismatica_ (Pl. 39, fig. 6) in the possession of a medullary
shell and the absence of the tube edges.

_Dimensions._--Main axis of the ellipsoid 0.14, equatorial axis 0.12, pores
0.01, bars 0.003; length of the tubes 0.15 or more, breadth 0.03. Medullary
shell 0.03, pores 0.002, bars 0.001.

_Habitat._--Pacific, central area, Stations 265 to 268, depth 2700 to 2900
fathoms.

4. _Pipetta conus_, n. sp.

Cortical shell spindle-shaped, the middle ellipsoidal part gently passing
over at both poles into the conical tubes, which attain only half its
length. Network irregular, with roundish or subcircular pores, twice to
three times as broad as the bars, twelve to sixteen on the half equator.
Medullary shell spherical, one-fourth as broad as the cortical. (Differs
from the foregoing species in the short conical tubes and the irregular
reticulation.)

_Dimensions._--Middle part of the cortical shell 0.16 long, 0.13 broad;
tubes 0.09 long, 0.05 on the base broad; pores 0.005 to 0.01, bars 0.003.
Medullary shell 0.04.

_Habitat._--North Pacific, Station 241, depth 2300 fathoms.

Genus 143. _Pipettaria_,[182] n. gen.

_Definition._--#Druppulida# with simple ellipsoidal cortical shell and
double medullary shell, with two hollow fenestrated tubes opposite on both
poles of the main axis.

The genus _Pipettaria_ differs from the foregoing _Pipetta_ only in the
duplication of the medullary shell; as in this, the tubular prolongations
of the main axis of the cortical shell may be either conical (with closed
apex) or cylindrical (with apical opening?).

{339}1. _Pipettaria fusaria_, n. sp.

Cortical shell spindle-shaped, the middle ellipsoidal part gently passing
over on both poles into the conical tubes, which attain about half its
length. Pores regular, circular, twice as broad as the bars, sixteen to
eighteen on the half equator; pores of the tubes smaller. Both medullary
shells spheroidal, compressed. (The appearance of the cortical shell
resembles that of _Cannartiscus amphiconus_, Pl. 39, fig. 19, but without
the equatorial constriction.)

_Dimensions._--Main axis of the ellipsoid 0.15, equatorial axis 0.13;
length of the polar tubes 0.08, basal breadth 0.05; pores of the former
0.008, bars 0.004; diameter of the medullary shells 0.04 and 0.02.

_Habitat._--South Pacific, Station 300, depth 1375 fathoms.

2. _Pipettaria tubaria_, n. sp. (Pl. 39, fig. 15).

  _Cannartidium tubarium_, Haeckel, 1882, Atlas (pl. xxxix. fig. 15).

Cortical shell ellipsoidal, on both poles distinctly separated from the
short conical tubes, the length and breadth of which equal the outer
medullary shell. In the equatorial plane arises a circle of four to six
short conical protuberances, similar to the polar tubes. Pores subregular,
circular, or roundish, scarcely broader than the bars, sixteen to twenty on
the half equator. Both medullary shells spheroidal, somewhat compressed in
the direction of the two poles (as in fig. 18_a_).

_Dimensions._--Main axis of the ellipsoid 0.12, equatorial axis 0.09; pores
0.005, bars 0.004; size of the equatorial protuberances and of the polar
tubes 0.02.

_Habitat._--Pacific, central area, Station 265, depth 2900 fathoms.

Family XIII. #SPONGURIDA#, Haeckel (Pl. 48, figs. 6, 7).

_Spongurida_, Haeckel, 1862, Monogr. d. Radiol., p. 447 (_sensu emendato_).

_Definition._--#Prunoidea# with spongy ellipsoidal or cylindrical shell,
composed wholly or partially of a spongy framework, without equatorial
stricture, with or without an enclosed medullary shell.

The family #Spongurida# comprises, in the sense here restricted, all those
#Prunoidea# in which the ellipsoidal or cylindrical shell is composed
wholly or partially of an irregular siliceous framework, not of simple
lattice-work. It contains two subfamilies, differing in the absence or
presence of a latticed medullary shell in the middle of the central
capsule; in the Spongellipsida it is absent, in the Spongodruppida present;
the former are most nearly related to the Ellipsida, the latter to the
Druppulida, the difference consisting only in the spongy structure of the
cortical shell.

In my Monograph (1862, p. 447) the family Spongurida had a much wider
extent, comprising also a number of #Sphæroidea# and #Discoidea#, agreeing
in the spongy {340}structure of the shell. Here we restrict the definition
to those spongy #Sphærellaria# in which the central capsule and the
enclosing spongy cortical shell are ellipsoidal or cylindrical, therefore
each transverse section is a circle, and each meridional section an
ellipse, as in all #Prunoidea#.

_The Cortical Shell_ in all Spongurida is composed of a delicate framework
of irregularly branched and interwoven siliceous threads; commonly this
spongy structure is rather dense or compact, but sometimes also very loose.
In the simplest form, _Spongellipsis_, the spongy cortical shell contains a
large cavity, in which lies freely the central capsule. In _Spongurus_ this
cavity is completely distended by a spongy framework. In this case the
solid spongy shell becomes often prolonged, and its original ellipsoidal
form passes over into a cylindrical one (as in many Zygartida). Sometimes
(particularly in _Spongocore_, Pl. 48, fig. 6) the cylinder becomes
three-jointed by two more or less distinct annular constrictions.
_Spongocore_ is distinguished by an outer veil, a thin lattice-lamella,
which envelops the spongy shell and is connected with it by radial beams.

_The Medullary Shell_, absent in the Spongellipsida, is constant in the
second subfamily Spongodruppida. It is either a simple latticed shell
(_Spongodruppa_) or double, composed of two concentric latticed shells
(_Spongoliva_); its form is either spherical or ellipsoidal. It lies in the
middle of the central capsule, and is connected by radial beams
(perforating the membrane of the latter) with the enveloping spongy
cortical shell.

In many Spongurida the surface of the shell is armed with radial spines,
and in some genera (_Spongoprunum_, _Spongatractus_, &c., Pl. 17, fig. 12),
on both poles of the main axis, are developed two strong opposite polar
spines, as in many other #Prunoidea#.

_The Central Capsule_ of the Spongurida is either ellipsoidal or
cylindrical. Only in _Spongellipsis_ it lies freely in the internal cavity
of the spongy shell. In all other genera it is perforated by a part of the
skeleton; in the Spongodruppida it contains the simple or double medullary
shell, and the radial beams which perforate its membrane and connect the
latter with the external spongy cortical shell. In _Spongurus_ and the
allied genera (_Spongocore_, _Spongoprunum_) the whole central capsule is
filled with a spongy framework which also envelops its surface.

{341}_Synopsis of the Genera of Spongurida._

  -------------------------------------------------------------------------
  I. Subfamily Spongellipsida.
     (Ellipsoidal shell composed only of a spongy framework without a
     latticed medullary shell in the centre.)
  -------------------------------------------------------------------------
  Spongy shell     }No polar spines,     144. _Spongellipsis_.
    with internal  }
    cavity.        }

                   {Without lattice
  Spongy shell     {  mantle. No polar
    solid, without {  spines,            145. _Spongurus_.
    internal       {
    cavity.        {With lattice
                   {  mantle.
                   { No polar spines,    146. _Spongocore_.
                   {
                   {Without lattice
                   {  mantle. Two
                   {  opposite spines
                   {  on the poles of
                   {  the axis,          147. _Spongoprunum_
  -------------------------------------------------------------------------
  II. Subfamily Spongodruppida.
      (Ellipsoidal shell composed of an outer spongy cortical shell and an
      inner latticed medullary shell.)
  -------------------------------------------------------------------------
  Medullary shell  {No polar spines,     148. _Spongodruppa_.
    simple.        {
                   {Two opposite spines
                   {  on the poles of
                   {  the axis,          149. _Spongatractus_.

  Medullary shell  {No polar spines,     150. _Spongoliva_.
    double.        {
                   {
                   {Two opposite spines
                   {  on the poles of
                   {  the axis,          151. _Spongoxiphus_.

Subfamily 1. SPONGELLIPSIDA, Haeckel.

_Definition._--#Spongurida# with a spongy ellipsoidal or cylindrical shell,
without an internal latticed medullary shell.

Genus 144. _Spongellipsis_,[183] n. gen.

_Definition._--#Spongurida# with an ellipsoidal or cylindrical spongy
shell, containing an internal cavity, without a latticed medullary shell.
Polar spines absent.

The genus _Spongellipsis_ embraces those very simple Spongurida in which
the ellipsoidal central capsule is enclosed in a spongy cortical shell of
the same form. It corresponds, therefore, to _Plegmosphæra_ among the
#Sphæroidea#, to _Plegmodiscus_ among the #Discoidea#, and to
_Spongolarcus_ among the #Larcoidea#. In some species the ellipsoidal form
is prolonged and passes into a cylindrical one.

Subgenus 1. _Spongellipsarium_, Haeckel.

_Definition._--Surface of the shell smooth or rough, without radial spines.

{342}1. _Spongellipsis lævis_, n. sp.

Shell ellipsoidal, with smooth surface, its spongy wall scarcely one-tenth
as thick as the minor axis of the inner cavity. Spongy framework very
compact, with small meshes, three to six times as broad as the bars.
Proportion of the major axis to the minor = 3 : 2.

_Dimensions._--Major axis (or length) of the shell 0.36, minor axis (or
breadth) 0.24.

_Habitat._--Pacific, central area, Station 265, surface.

2. _Spongellipsis aspera_, n. sp.

Shell ellipsoidal, with rough surface, its spongy wall nearly half as thick
as the minor axis of the inner cavity. Spongy framework very loose, with
large meshes, ten to twenty times as broad as the bars. Proportion of the
major axis to the minor = 4 : 3.

_Dimensions._--Length of the shell 0.24, breadth 0.18.

_Habitat._--North Pacific, Station 253, surface.

3. _Spongellipsis aplysina_, n. sp.

Shell nearly cylindrical, with rough surface, its spongy wall about
one-fourth as thick as the minor axis of the internal cavity. Spongy
framework loose, with large meshes, four to eight times as broad as the
bars. Proportion of both axes = 6 : 1. (Similar to a spongy cylinder of
Aplysina.)

_Dimensions._--Length of the shell 0.3, breadth 0.05.

_Habitat._--North Atlantic, Station 64, surface.

Subgenus 2. _Spongellipsidium_, Haeckel.

_Definition._--Surface of the shell covered with radial spines.

4. _Spongellipsis setosa_, n. sp.

Shell ellipsoidal, covered with numerous (sixty to eighty) thin,
bristle-shaped, radial spines, about half as long as the major axis. Spongy
framework loose, with large meshes, ten to twenty times as broad as the
bars. Minor axis of the inner cavity twice as long as the thickness of the
spongy wall. Proportion of both axes = 5 : 3.

_Dimensions._--Length of the shell 0.2, breadth 0.12.

_Habitat._--South Atlantic, Station 325, surface.

5. _Spongellipsis spinosa_, n. sp.

Shell nearly cylindrical, covered with numerous thorns and thirty to forty
larger conical radial spines, somewhat longer than the major axis. Spongy
framework compact, with small meshes, four {343}to eight times as broad as
the bars. Minor axis of the inner cavity about six times as large as the
thickness of the spongy wall. Proportion of both axes = 4 : 1.

_Dimensions._--Length of the shell 0.24, breadth 0.06.

_Habitat._--South Pacific, Station 300, surface.

Genus 145. _Spongurus_,[184] Haeckel, 1862, Monogr. d. Radiol., p. 465.

_Definition._--#Spongurida# with ellipsoidal or cylindrical (sometimes
three-jointed) shell, of solid spongy framework, without internal cavity
and without latticed medullary shell. Polar spines and outer lattice-mantle
absent.

The genus _Spongurus_ was founded by me in 1862 for the common cosmopolitan
_Spongurus cylindricus_, a massive spongy cylinder with radial spines. I
enlarge here the conception of the genus, in receiving also ellipsoidal,
massive spongy #Prunoidea#, with or without radial spines. Sometimes the
cylindrical shell is more or less distinctly three-jointed, with two
annular strictures, as also in the following and nearly allied genus.

Subgenus 1. _Spongurantha_, Haeckel.

_Definition._--Spongy framework everywhere of the same structure; surface
smooth or rough, but without radial spines.

1. _Spongurus stuparius_, n. sp.

Shell ellipsoidal, one and a half times as long as broad, with nearly
smooth surface. Spongy framework everywhere of equal structure, with small
meshes, four to six times as broad as the bars.

_Dimensions._--Length of the shell (or major axis) 0.2, breadth of it (or
minor axis) 0.14.

_Habitat._--South Pacific, Station 295, depth 1500 fathoms.

2. _Spongurus stypticus_, n. sp.

Shell ellipsoidal, twice as long as broad, with thorny surface. Spongy
framework everywhere of equal structure, with large meshes, ten to twenty
times as broad as the bars.

_Dimensions._--Length of the shell 0.3, breadth 0.15.

_Habitat._--Pacific, central area, Station 274, depth 2750 fathoms.

3. _Spongurus phalanga_, Haeckel.

  _Spongurus cylindricus_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 119,
  Taf. vii. fig. 3.

Shell nearly cylindrical, five times as long as broad, with thorny surface.
Spongy framework compact, everywhere of equal structure, with small meshes,
scarcely broader than the bars.

{344}_Dimensions._--Length of the shell 0.24, breadth 0.05.

_Habitat._--Pacific, central area, Station 268, depth 2600 fathoms; fossil
in the Tertiary rocks of Sicily, Stöhr.

Subgenus 2. _Spongurella_, Haeckel.

_Definition._--Spongy framework everywhere of the same structure; surface
armed with radial spines.

4. _Spongurus asper_, Haeckel.

  _Haliomma asperum_, Joh. Müller, 1858, Abhandl. d. k. Akad. d. Wiss.
  Berlin, p. 40, Taf. ii. fig. 2.

  _Haliomma asperum_, Haeckel, 1862, Monogr. d. Radiol., p. 431.

Shell ellipsoidal, one and a third times as long as broad, with thorny
surface and twenty symmetrically disposed, thin, bristle-shaped, radial
spines, about as long as the shell. Spongy framework everywhere of the same
structure, very compact, with small meshes, three to four times as broad as
the bars.

_Dimensions._--Length of the shell 0.11, breadth 0.08.

_Habitat._--Mediterranean, Ligurian coast (J. Müller), Portofino (Haeckel).

5. _Spongurus cylindricus_, Haeckel.

  _Spongurus cylindricus_, Haeckel, 1862, Monogr. d. Radiol., p. 465, Taf.
  xxvii. fig. 1.

Shell cylindrical, four to five times as long as broad, with nearly smooth
surface, and twenty to thirty thin, bristle-shaped, radial spines, about
half as long as the shell. Spongy framework everywhere of the same
structure, very compact, with small meshes, scarcely broader than the bars.

_Dimensions._--Length of the shell 0.2, breadth 0.04 to 0.05.

_Habitat._--Cosmopolitan; Mediterranean, Atlantic, and Pacific, surface.

6. _Spongurus tricolus_, n. sp.

Shell nearly cylindrical, with two slight annular transverse strictures;
its middle part is somewhat broader. Surface thorny, with numerous (forty
to sixty or more) short, thin, radial spines, not longer than the breadth
of the shell. Spongy framework everywhere of the same structure, compact,
with small meshes, twice to three times as broad as the bars.

_Dimensions._--Length of the shell 0.24, breadth 0.04 to 0.06.

_Habitat._--Pacific, central area, Station 272, 2600 fathoms.

Subgenus 3. _Sponguroma_, Haeckel.

_Definition._--Spongy framework in the inner part of the shell very
compact, in the outer part very loose; surface armed with radial spines.

{345}7. _Spongurus radians_, n. sp.

Shell ellipsoidal, one and a half times as long as broad, with thorny
surface, and eighty to one hundred and twenty (or more) thin,
bristle-shaped, radial spines, somewhat longer than the shell. Spongy
framework in the inner part very compact, in the outer part very loose,
with a gradual transition between the two parts. Meshes in the central part
not broader than the bars, in the superficial part ten to twenty times as
broad.

_Dimensions._--Length of the shell 0.24, breadth 0.16.

_Habitat._--Mediterranean, Portofino, near Genoa, Haeckel, surface.

8. _Spongurus spongechinus_, n. sp.

Shell ellipsoidal, one and a third times as long as broad, with thorny
surface, and thirty to forty thick, conical radial spines, about half as
long as the shell. Spongy framework in the inner part of the shell compact,
in the outer loose, with a gradual transition between the two parts. Meshes
in the central part smaller than the bars, in the superficial part four to
eight times as broad.

_Dimensions._--Length of the shell 0.18, breadth 0.14.

_Habitat._--North Atlantic, Station 353, surface.

Genus 146. _Spongocore_,[185] n. gen.

_Definition._--#Spongurida# with ellipsoidal or cylindrical (sometimes
three-jointed) shell of solid spongy framework, without internal cavity and
without latticed medullary shell. Polar spines absent. An outer
lattice-mantle is connected with the spongy shell by radial beams.

The genus _Spongocore_ contains some widely distributed Spongurida, which
are distinguished from the nearly related _Spongurus_ by the development of
a peculiar veil or mantle of delicate lattice-work, which envelops either