may therefore be regarded as the common ancestral form of this subfamily.
The thorax exhibits three radial ribs, which are completely enclosed in its
wall. Sethopera may be derived either from _Dictyophimus_ or from another
of the Sethopilida (_Lamprodiscus, Clathrocanium_) by development of a
basal lattice-plate closing the mouth. There are often wide holes or open
spaces between the three radial ribs.
1. _Sethopera tricostata_, n. sp. (Pl. 97, fig. 11).
Cephalis subspherical, spinulate, with a pyramidal horn of the same length.
Length of the two joints = 5 : 8, breadth = 5 : 8. Thorax also nearly
spherical; in the upper half with three stout, prismatic, convex, divergent
ribs, and three large ovate holes between them; in the lower half with
numerous small and irregular pores, spinulate.
_Dimensions._--Cephalis 0.05 diameter; thorax 0.08 diameter.
_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.
2. _Sethopera oceania_, Haeckel.
_Lithopera oceania_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 297, Taf. iv. fig. 21.
Cephalis hemispherical, with a small bristle-shaped horn of half the length
(broken off in Ehrenberg's figure). Length of the two joints = 3 : 4,
breadth = 3 : 4. Thorax nearly spherical; in the upper half with three
divergent ribs, separated by some larger, irregular pores; in the lower
half with numerous small, irregular, roundish pores.
_Dimensions._--Cephalis 0.03 long, 0.03 broad; thorax 0.04 long, 0.04
broad.
_Habitat._--North Atlantic, Station 354, surface; Canary Islands and
Azores.
3. _Sethopera pyrum_, Haeckel.
? _Lithopera pyrum_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 297.
Cephalis hemispherical, with a small conical horn of half the length.
Length of the two joints = 3 : 10, breadth = 3 : 7. Thorax pear-shaped,
with rather large, regular, quincuncial pores; {1233}its upper half with
three divergent ribs in the wall, half as broad as the subspherical lower
half. (The three ribs probably were overlooked by Ehrenberg.)
_Dimensions._--Cephalis 0.03 long, 0.03 broad; thorax 0.1 long, 0.07 broad.
_Habitat._--North Pacific, Station 256, surface; Californian Sea, 2600
fathoms, Ehrenberg.
4. _Sethopera lagena_, Haeckel.
_Lithopera lagena_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 78, Taf. iii. fig. 4.
Cephalis pear-shaped, with a small conical horn of half the length. Length
of the two joints = 3 : 8, breadth = 3 : 6. Thorax smooth, pear-shaped,
with irregular roundish pores; in the wall of its upper third three
divergent thin ribs (sometimes wanting); the lower half inflated. (Compare
_Sethocapsa lagena_.)
_Dimensions._--Cephalis 0.03 long, 0.03 broad; thorax 0.08 long, 0.06
broad.
_Habitat._--Fossil in Barbados.
Genus 551. _Lithopera_,[168] Ehrenberg, 1847, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 54.
_Definition._--#Sethoperida# (vel Dicyrtida triradiata clausa), with three
divergent ribs enclosed in the cavity of the thorax. Cephalis with a horn.
The genus _Lithopera_ is, like the preceding _Sethopera_, one of the most
simple and oldest forms of the Sethoperida, and exhibits three divergent
thoracic ribs, which are prolonged neither into lateral wings nor into
basal feet. But whilst in _Sethopera_ the three ribs are enclosed in the
lattice-work of the shell-wall, in _Lithopera_ they lie freely in its
cavity, and are overgrown by the enveloping shell-wall, being inserted on
its inner face with their distal ends. _Lithopera_ may be derived directly
from _Lithomelissa_, by development of lattice-work closing the
shell-mouth. Therefore the lower part of the cephalis is hidden in the
uppermost part of the thorax; only its upper part is free.
1. _Lithopera bacca_, Ehrenberg.
_Lithopera bacca_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin,
p. 297, Taf. viii. fig. 1.
Cephalis spherical, with small, irregular pores and a bristle-shaped spine
of half the length; its lower half hidden in the thorax. Length of the two
joints = 1 : 6, breadth = 1 : 5. Thorax ellipsoidal, smooth, with regular,
hexagonal, small pores, and very thin, thread-like bars. From the deep
collar stricture there arise three internal, divergent bars, which are
inserted at the uppermost third of the thorax.
_Dimensions._--Cephalis 0.02 diameter; thorax 0.12 long, 0.1 broad.
_Habitat._--Tropical Pacific, Stations 200, 224, 266, 271, &c., surface.
{1234}2. _Lithopera bursella_, Ehrenberg.
_Lithopera bursella_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 297, Taf. x. fig. 4.
Shell of about the same form and structure as in the nearly allied
preceding species, but smaller, of more slender form, with smaller pores
and thinner bars. Length of the two joints = 1 : 5, breadth = 1 : 3. In the
specimen observed by me the three internal, divergent bars of the
ellipsoidal thorax (not seen by Ehrenberg) were as distinct as in the
similar preceding and following species.
_Dimensions._--Cephalis 0.02 diameter; thorax 0.1 long, 0.06 broad.
_Habitat._--Indian Ocean, Zanzibar (Pullen), Madagascar (Rabbe), surface.
3. _Lithopera ananassa_, n. sp. (Pl. 57, fig. 3).
Shell of about the same form and structure as in the two preceding species,
but larger and more robust, and differing in the spiny surface. Length of
the two joints = 1 : 5, breadth = 1 : 4. Here also the lower half of the
spherical cephalis is submerged in the ellipsoidal thorax, and from the
collar stricture arise three strong, internal, divergent beams. The bars of
the hexagonal pores are much thicker than in the two preceding species.
_Dimensions._--Cephalis 0.03 diameter; thorax 0.16 long, 0.12 broad.
_Habitat._--Tropical Atlantic, Stations 347 to 352, surface.
4. _Lithopera globosa_, n. sp.
Cephalis spherical, very small, with two divergent conical horns of half
the length; its lower half hidden in the thorax. Length of the two joints =
1 : 5, breadth = 1 : 5. Thorax spherical, with regular, circular,
hexagonally-framed pores. From the collar stricture arise three radial
internal beams, horizontally diverging, and inserted at the inside of the
thorax.
_Dimensions._--Cephalis 0.03 diameter; thorax 0.15 diameter.
_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.
5. _Lithopera gutta_, Ehrenberg.
_Lithopera gutta_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin,
p. 297, Taf. viii. fig. 2.
Shell pear-shaped, with sharp collar stricture. Length of the two joints =
1 : 4, breadth = 1 : 3. Cephalis spherical, with a conical horn of the same
length; its lower half hidden in the uppermost part of the ovate thorax,
and connected with its wall by three internal, cortinar beams. Pores of the
thorax very irregular in form and size, partly lobed.
_Dimensions._--Cephalis 0.02 diameter; thorax 0.08 long, 0.06 broad.
_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms;
Philippine Sea (depth 3300 fathoms), Ehrenberg.
{1235}Genus 552. _Micromelissa_,[169] Haeckel, 1881, Prodromus, p. 433.
_Definition._--#Sethoperida# (vel Dicyrtida triradiata clausa), with three
divergent, solid, lateral wings. Cephalis with a horn.
The genus _Micromelissa_ differs from the two preceding genera in the free
prominence of the three cortinar ribs, forming three solid lateral wings.
Beyond these the thorax walls are convergent, and the basal mouth closed by
a lattice-plate. Therefore _Micromelissa_ may have arisen from
_Lithomelissa_ simply by development of this basal mouth-plate.
1. _Micromelissa bombus_, n. sp. (Pl. 57, fig. 14).
Shell smooth, with sharp collar stricture. Length of the two joints =
1 : 4, breadth = 1 : 5. Cephalis spherical, with an oblique conical horn of
the same length. Thorax subspherical, in the upper half with three conical,
downwardly diverging wings, about as long as its radius. Pores very small
and scarce.
_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax 0.09 long, 0.1 broad.
_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.
2. _Micromelissa vespa_, n. sp.
Shell smooth, with deep collar stricture. Length of the two joints = 2 : 5,
breadth = 2 : 3. Cephalis spherical, with an oblique pyramidal horn twice
the length. Thorax inversely ovate, in the upper half with three pyramidal
wings, which are equal to its breadth, little curved and diverging
downwards. Pores very small and scarce.
_Dimensions._--Cephalis 0.04 diameter; thorax 0.1 long, 0.06 broad.
_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.
3. _Micromelissa apis_, n. sp.
Shell rough, with deep collar stricture. Length of the two joints = 2 : 3,
breadth = 2 : 4. Cephalis subspherical, with a straight conical horn of
half the length, and subregular, circular, double-contoured pores, of the
same breadth as the bars. Thorax little larger, subspherical, with
irregular, roundish pores, twice to four times as broad as the bars. From
its lower half arise three short conical wings, curved downwards, and half
as long as the cephalis.
_Dimensions._--Cephalis 0.04 long, 0.04 broad; thorax 0.06 long, 0.08
broad.
_Habitat._--South Pacific, Station 295, depth 1500 fathoms.
{1236}4. _Micromelissa microptera_, Haeckel.
_Lithomelissa microptera_, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig.
2; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 78, Taf. iii. fig. 13.
_Lithomelissa microptera_, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol.
xxxvi. p. 539, Taf. xxxiii. fig. 26.
Shell smooth, with distinct collar stricture. Length of the two joints =
4 : 6, breadth = 3 : 5. Cephalis ovate, with a straight sword-shaped horn
of the same length and very small pores, some larger ones above the
stricture. Thorax little larger, ovate, nearly hyaline, with very few and
small scattered pores. From its uppermost part arise three short conical
wings, scarcely half as long as the cephalic horn, little curved and
divergent downwards.
_Dimensions._--Cephalis 0.04 long, 0.03 broad; thorax 0.06 long, 0.05
broad.
_Habitat._--Fossil in Barbados.
5. _Micromelissa ventricosa_, Haeckel.
_Lithomelissa ventricosa_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 78, Taf. iii. fig. 11.
Shell rough, with slight collar stricture. Length of the two joints =
1 : 7, breadth = 1 : 5. Cephalis small, hemispherical, with a small conical
horn of half the length. Thorax ovate, very large, papillate, with
irregular, roundish pores. From its basal part arise three short and stout
conical wings at great distances, shorter than the cephalis. (A
transition-form to _Sethocapsa_.)
_Dimensions._--Cephalis 0.02 long, 0.022 broad; thorax 0.14 long, 0.11
broad.
_Habitat._--Fossil in Barbados.
Genus 553. _Peromelissa_,[170] Haeckel, 1881, Prodromus, p. 433.
_Definition._--#Sethoperida# (vel Dicyrtida triradiata clausa) with three
divergent solid lateral wings. Cephalis without horn.
The genus _Peromelissa_ differs from the preceding ancestral form,
_Micromelissa_, only in the absence of the cephalic horn, which is lost by
reduction.
1. _Peromelissa phalacra_, n. sp. (Pl. 57, fig. 11).
Shell smooth, with two joints of nearly equal size and similar ovate form.
Cephalis in the upper half hyaline, without pores; in the lower half with
four remote, transverse rows of irregular, roundish pores, decreasing in
size towards the hemispherical summit. Thorax with twelve transverse
{1237}rows of pores, the upper six rows three to four times as large as the
lower six rows. From its upper half diverge almost horizontally three
angular club-shaped wings, half as long as the shell.
_Dimensions._--Cephalis 0.05 long, 0.06 broad; thorax 0.06 long, 0.05
broad.
_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.
2. _Peromelissa psilocrana_, n. sp.
Shell smooth, very similar to the preceding species in size and form, but
differing from it in the disposition of the irregular, roundish pores,
which are irregularly scattered, and in the form of the three wings, which
are slender, pyramidal, diverging downwards, and about as long as the
entire shell.
_Dimensions._--Cephalis 0.07 long, 0.06 broad; thorax 0.07 long, 0.06
broad.
_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.
3. _Peromelissa capito_, Haeckel.
_Lithomelissa capito_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 78, Taf. iii. fig. 14.
Shell rough, with two joints of nearly equal size and similar ovate form.
Pores irregular, roundish, everywhere scattered. From the upper half of the
thorax arise three short conical wings, which are little curved and diverge
downwards (scarcely half as long as the breadth of the shell).
_Dimensions._--Cephalis 0.07 long, 0.06 broad; thorax 0.07 long, 0.06
broad.
_Habitat._--Fossil in Barbados.
4. _Peromelissa calva_, n. sp. (Pl. 57, fig. 12).
Shell rough, with two ovate joints of somewhat different sizes. Pores
irregular, roundish, everywhere scattered. Thorax little larger than the
cephalis; from its upper half arise three short conical wings, diverging
downwardly or nearly horizontally.
_Dimensions._--Cephalis 0.06 long, 0.04 broad; thorax 0.07 long, 0.05
broad.
_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.
Genus 554. _Sethomelissa_,[171] Haeckel, 1881, Prodromus, p. 431.
_Definition._--#Sethoperida# (vel Dicyrtida triradiata clausa) with three
divergent latticed lateral wings. Cephalis with a horn (or a bunch of
horns).
The genus _Sethomelissa_ differs from the nearly allied _Micromelissa_ in
the fenestration of the three lateral wings, and may be derived either from
this genus by development of lattice-work connecting the three wings with
the shell, or perhaps from _Clathrocanium_ by closing the mouth.
{1238}1. _Sethomelissa hymenoptera_, n. sp.
Cephalis subspherical, thorny, with a bunch of three divergent, larger
apical spines. Thorax pear-shaped, with three broad, triangular, latticed
wings, the superior edge of which is a horizontal, straight, and stout
spine, nearly as long as the thorax. Pores irregular, roundish.
_Dimensions._--Cephalis 0.03 diameter; thorax 0.11 long, 0.08 broad.
_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.
Genus 555. _Tetrahedrina_,[172] Haeckel, 1881, Prodromus, p. 433.
_Definition._--#Sethoperida# (vel Dicyrtida triradiata clausa) with a
three-sided pyramidal thorax, the three edges of which are prolonged into
three divergent, solid, terminal feet. Cephalis with a horn.
The genus _Tetrahedrina_, and the two following nearly allied genera, are
distinguished by the possession of three free, divergent, terminal feet,
projecting over the latticed mouth of the thorax. _Tetrahedrina_ may be
derived directly from _Dictyophimus_, by development of a horizontal
latticed mouth-plate from the middle part of the feet, the lower part of
which remains free. This genus, not noticed by Ehrenberg, is similar to his
_Lithochytris_, and common in the Barbados deposits.
1. _Tetrahedrina pyramidalis_, n. sp.
Shell three-sided pyramidal, smooth, with slight collar stricture. Length
of the two joints = 1 : 4, breadth = 1 : 4. Cephalis hemispherical, with
small, sparsely disposed pores, and a pyramidal horn of the same length.
Thorax with subregular, circular pores and three sharp edges, prolonged
into three divergent pyramidal feet of the same length.
_Dimensions._--Cephalis 0.03 diameter; thorax 0.12 long, 0.12 broad.
_Habitat._--Fossil in Barbados.
2. _Tetrahedrina pyriformis_, n. sp.
Shell pear-shaped, rough, with distinct collar stricture. Length of the two
joints = 2 : 6, breadth = 2 : 5. Cephalis subspherical, with a conical horn
of the same length. Thorax with subregular, circular pores, ovate, at the
broad base with three pyramidal, widely divergent feet of the same length.
(Similar to _Lychnocanium tribulus_, Ehrenberg, 1875, _loc. cit._, pl. vii.
fig. 1, but with the mouth closed by a lattice-plate.)
_Dimensions._--Cephalis 0.04 diameter; thorax 0.12 long, 0.1 broad,
_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.
{1239}3. _Tetrahedrina quadricornis_, Haeckel.
_Lithochytris triangula_, Bury, 1862, Polycystins of Barbados, pl. xix.
figs. 4, 5, 6.
Shell pear-shaped, papillate, with slight collar stricture. Length of the
two joints = 1 : 5, breadth = 1 : 5. Cephalis subspherical, with a stout
conical horn twice the length. Thorax with irregular, roundish, lobulated
pores, with three conical, stout, divergent feet at the base, of the same
size and form as the cephalic horn.
_Dimensions._--Cephalis 0.02 diameter; thorax 0.1 long, 0.1 broad.
_Habitat._--Fossil in Barbados.
Genus 556. _Sethochytris_,[173] Haeckel, 1881, Prodromus, p. 433.
_Definition._--#Sethoperida# (vel Dicyrtida triradiata clausa) with three
terminal latticed feet or hollow, fenestrated, divergent, basal apophyses
of the thorax. Cephalis with a horn.
The genus _Sethochytris_ differs from the preceding _Tetrahedrina_ in the
fenestration of the three basal feet, which form direct protrusions or
evaginations of the three basal corners of the pyramidal shell. It may be
derived from _Sethopera_ by centrifugal growth of the basal corners.
1. _Sethochytris triconiscus_, n. sp. (Pl. 57, fig. 13).
Shell rough, with deep collar stricture. Length of the two joints = 1 : 8,
breadth = 1 : 3. Cephalis spherical, with an oblique pyramidal horn of the
same length. Thorax campanulate, conical; its three basal corners prolonged
into three divergent, slender, hollow, fenestrated cones, twice as long as
the thorax, and ending in a stout pyramidal spine.
_Dimensions._--Cephalis 0.04 diameter, thorax 0.12 diameter, length of the
feet 0.2.
_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.
2. _Sethochytris barbadensis_, Haeckel.
_Lithochytris barbadensis_, Ehrenberg, 1875, Abhandl. d. k. Akad. d.
Wiss. Berlin, p. 160, Taf. v. fig. 2.
Shell smooth, with slight collar stricture. Length of the two joints =
1 : 6, breadth = 1 : 4. Cephalis ovate, with a conical horn of half the
length. Thorax conical; its base prolonged into three divergent, hollow,
fenestrated cones, half as long as the thorax. Pores small, subregular,
circular.
_Dimensions._--Cephalis 0.025 diameter, thorax 0.1 diameter, length of the
feet 0.05.
_Habitat._--Fossil in Barbados.
{1240}3. _Sethochytris pyramis_, n. sp.
Shell smooth, with slight collar stricture. Length of the two joints =
1 : 8, breadth = 1 : 5. Cephalis ovate, with a conical horn of half the
length. Thorax pyramidal, with three sharp edges; its base prolonged into
three pyramidal, divergent, hollow, fenestrated feet, nearly as long as the
thorax. Pores regular, circular, double-contoured.
_Dimensions._--Cephalis 0.04 diameter; thorax 0.2 diameter, length of the
feet 0.15.
_Habitat._--Central Pacific, Station 265, depth 2900 fathoms; also fossil
in Barbados.
4. _Sethochytris triangula_, Haeckel.
_Lithochytris triangula_, Bury, 1862, Polycystins of Barbados, pl. xix.
fig. 7.
Shell rough, with obliterated collar stricture (but distinct internal
collar septum). Length of the two joints = 1 : 6, breadth = 1 : 3. Cephalis
subspherical, with a stout conical horn of the same length. Thorax
pear-shaped, inflated; its base prolonged into three divergent, hollow,
fenestrated cones, about as long as the thorax. Pores regular, circular.
_Dimensions._--Cephalis 0.03 diameter; thorax 0.09 diameter, length of the
feet 0.1.
_Habitat._--Fossil in Barbados.
Genus 557. _Clathrolychnus_,[174] Haeckel, 1881, Prodromus, p. 431.
_Definition._--#Sethoperida# (vel Dicyrtida triradiata clausa), with three
vertical, lateral latticed wings stretched between the apical horn and the
three terminal feet. The external lattice-work connecting the wings and
closing the mouth forms an arachnoidal mantle around the shell.
The genus _Clathrolychnus_ may be derived directly from _Clathrocorys_, by
development of an external arachnoidal mantle connecting the three wings
and the three feet, and enveloping the whole shell, closing at the same
time the basal mouth of the thorax by a fenestrated plate.
1. _Clathrolychnus araneosus_, n. sp. (Pl. 64, fig. 5).
Cephalis subspherical, with irregular, polygonal pores and a large
pyramidal horn of twice the length. Length of the two joints = 4 : 9,
breadth = 5 : 12. Thorax with three large triangular holes (twice as broad
as the cephalis) between the three pyramidal, divergent feet, which at the
distal end are connected by a narrow band of network, composed of two or
three rows of polygonal pores. The entire pyramidal shell is enveloped by a
very delicate web of irregular, polygonal {1241}meshes, closing also the
basal mouth. (In fig. 5 the greater part of the web is taken off to
demonstrate the large holes of the thorax). Only two feet are visible.
_Dimensions._--Cephalis 0.04 long, 0.05 broad; thorax 0.09 long, 0.12
broad.
_Habitat._--Central Pacific, Station 274, surface.
2. _Clathrolychnus periplectus_, n. sp. (Pl. 64, fig. 6).
Cephalis subspherical, with subregular, circular pores and a pyramidal horn
of the same length. Length of the two joints = 1 : 2, breadth = 1 : 3.
Thorax with three large elliptical holes between the three pyramidal,
divergent feet, which are connected at the distal end by a broad band of
network, composed of five to ten rows of polygonal pores. The entire
pyramidal shell is enveloped by a very delicate web, which on the sides is
composed of subregular, square meshes, and on the closed mouth of polygonal
meshes. (In fig. 6 only a part of the web is represented.)
_Dimensions._--0.04 long, 0.05 broad; thorax 0.08 long, 0.14 broad.
_Habitat._.--Central Pacific, Station 271, surface.
Family LXIII. #ANTHOCYRTIDA#, n. fam.
_Sethophormida et Sethophænida_, Haeckel, 1881, Prodromus, p. 432, 433.
_Definition._--#Dicyrtida# multiradiata. (#Cyrtoidea# with a two-jointed
shell, divided by a transverse constriction into cephalis and thorax, and
bearing numerous--four to nine or more--radial apophyses.)
The family #Anthocyrtida#, composed of the Sethophormida and Sethophænida
of my Prodromus, comprises those #Cyrtoidea# in which the shell is
two-jointed and bears numerous radial apophyses. The two subfamilies differ
in the shape of the mouth, which in the Sethophormida is a simple, wide
opening; in the Sethophænida closed by a lattice-plate.
Numerous fossil and living forms of Anthocyrtida were described formerly by
Ehrenberg in his genera _Carpocanium_ and _Anthocyrtis_. These, however,
represent only a small part of the whole family, which exhibits a great
variety in the composition of the lattice-work and in the number of radial
beams. The number of species here described amounts to one hundred and
forty, and these are disposed in fourteen genera (twelve Sethophormida and
two Sethophænida).
The Sethophormida may be again divided into two different groups or tribes,
the _Sethamphorida_ and _Carpocanida_; in the former the thorax bears
numerous radial ribs, enclosed in its wall; in the latter these ribs have
disappeared, and only a corona of terminal feet is developed around the
mouth. The shell of the former is usually pyramidal, with a widely open
mouth; of the latter ovate, with a constricted mouth. The mouth of the
thorax becomes perfectly closed in the Sethophænida.
{1242}The majority of the Anthocyrtida may be derived from the Polyspyrida
(_Petalospyris_, &c.) by reduction of the cephalis and loss of the sagittal
ring, as was suggested by Bütschli (1882, _loc. cit._). But another part
may also have arisen from the Tripocyrtida, by interpolation of secondary
radial apophyses between the three primary perradial apophyses. The
cephalis in this family is developed in all possible degrees, from one of a
considerable size to one very much reduced. If it becomes perfectly lost,
the Cyrtocalpida arise.
_Synopsis of the Genera of Anthocyrtida._
-------------------------------------------------------------------------
I. Subfamily Sethophormida.
Terminal mouth of the thorax a simple wide opening.
--------------------
Radial ribs thorny (rarely smooth) prolonged into free terminal feet
(cephalis commonly large, with one or more horns).
-------------------------------------------------------------------------
Shell flat, campanulate or nearly discoidal
(cephalis without horn), 558. _Sethophormis_.
Shell ovate, with constricted mouth
(without horn), 559. _Sethamphora_.
{ Meshes of the network simple, 560. _Sethopyramis_.
{
Shell slender { Meshes fenestrated by
pyramidal, with { secondary latticework, 561. _Plectopyramis_.
straight ribs. {
{ Meshes closed by spongy
{ framework, 562. _Spongopyramis_.
-------------------------------------------------------------------------
Radial ribs thorny (rarely smooth) prolonged into free terminal feet
(cephalis commonly large, with one or more horns).
-------------------------------------------------------------------------
Shell not enveloped by arachnoidal network, 563. _Acanthocorys_.
Shell enveloped by arachnoidal network, 564. _Arachnocorys_.
-------------------------------------------------------------------------
No ribs in the thorax. Peristome with free terminal feet.
-------------------------------------------------------------------------
{ { Six feet, 565. _Anthocyrtoma_.
{ Feet {
{ terminal, { Nine feet, 566. _Anthocyrtis_.
Cephalis { without {
well-developed { separate { Twelve or more
with an apical { peristome. { feet, 567. _Anthocyrtium_.
horn. {
{ Feet subterminal, outside the
{ constricted peristome, 568. _Anthocyrtidium_.
Cephalis rudimentary, hidden in the upper
part of the thorax, without horn, 569. _Carpocanium_.
-------------------------------------------------------------------------
II. Subfamily Sethophænida. Terminal mouth closed by a lattice-plate.
-------------------------------------------------------------------------
Thorax with lateral apophyses (four to six or
more wings), 570. _Sethophæna_.
Thorax with terminal apophyses (four to six or
more feet), 571. _Clistophæna_.
{1243}Subfamily 1. SETHOPHORMIDA, Haeckel, 1881, Prodromus, p. 432.
_Definition._--#Anthocyrtida# with the basal mouth of the shell open (vel
Dicyrtida multiradiata aperta).
Genus 558. _Sethophormis_, Haeckel,[175] 1881, Prodromus, p. 432.
_Definition._--#Sethophormida# (vel Dicyrtida multiradiata aperta) with
numerous radial ribs in the wall of the flat and broad campanulate or
nearly discoidal thorax. Cephalis also flat and broad, cap-shaped without
horn.
The genus _Sethophormis_ comprises a great number of widely distributed and
large Dicyrtida, all agreeing in the flat cap-shaped or nearly discoidal
form of the thorax, which has constantly a very delicate network, and is
pierced by numerous radial beams. Four of these are commonly primary and
direct prolongations of the four cortinar rods in the collar septum, whilst
the others are secondary or interpolated ribs. _Sethophormis_ may be
derived either from the triradial _Lamprodiscus_ by multiplication of the
ribs (or interpolation of secondary ribs between the three primary), or
from _Halicalyptra_ by development of transverse rods connecting its
terminal feet, and forming a ribbed thorax. Corresponding to the number of
the ribs, we may distinguish as subgenera (separate genera in my Prodromus,
1881, p. 432) _Tetraphormis_ with four, _Pentaphormis_ with five,
_Hexaphormis_ with six, _Octophormis_ with eight, _Enneaphormis_ with nine,
and _Astrophormis_ with ten to twenty or more ribs. The cephalis bears no
horn, and is usually large, flat, cap-shaped or hemispherical.
Subgenus 1. _Tetraphormis_, Haeckel, 1881, Prodromus, p. 432.
_Definition._--Thorax with four radial ribs opposite in pairs in two
meridional planes, perpendicular to one another. Collar septum with four
large pores.
1. _Sethophormis cruciata_, n. sp.
Cephalis very large, hemispherical with irregular, delicate network of
small square meshes. Thorax flatly campanulate, with delicate, regular
network of small hexagonal meshes. All bars very thin, thread-like. Four
stout radial thoracic ribs, crossed in pairs, lie in two meridional planes,
perpendicular to one another. Very similar to _Sethophormis aurelia_ (Pl.
55, figs. 3, 4), but not so flat, and with only four thoracic ribs.
Peristome or margin of the thoracic mouth smooth, circular.
_Dimensions._--Cephalis 0.04 long, 0.08 broad; thorax 0.12 long, 0.36
broad.
_Habitat._--Central Pacific, Station 271, surface.
{1244}2. _Sethophormis medusa_, n. sp.
Cephalis very large, flat, cap-shaped, with irregular, delicate network of
polygonal meshes. Thorax flat, campanulate, nearly hemispherical, with
delicate, irregular network of small polygonal meshes. All bars very thin,
thread-like. Four stout radial thoracic ribs, as in the preceding species.
Peristome denticulate.
_Dimensions._--Cephalis 0.03 long, 0.09 broad; thorax 0.15 long, 0.25
broad.
_Habitat._--North Pacific, Station 244, surface.
Subgenus 2. _Pentaphormis_, Haeckel, 1881, Prodromus, p. 432.
_Definition._--Thorax with five radial ribs, one of the three primary ribs
(the odd occipital rib) being simple, the two others (the paired lateral
ribs) forked.
3. _Sethophormis pentalactis_, n. sp. (Pl. 56, fig. 5).
Cephalis large, flat, hemispherical, with subregular, hexagonal pores.
Thorax flat, campanulate, nearly hemispherical; also with subregular,
hexagonal pores, and with five stout ribs. The three primary ribs of the
thorax are complete, and reach the peristome; the two secondary ribs (as
basal branches of the two lateral ribs) are incomplete and absent in the
distal half of the thorax. Peristome denticulate, with an elegant marginal
corona of small square pores and short conical spines.
_Dimensions._--Cephalis 0.03 long, 0.06 broad; thorax 0.1 long, 0.2 broad.
_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.
4. _Sethophormis asteriscus_, n. sp.
Cephalis large, flat, cap-shaped, with irregular polygonal pores. Thorax
flat, campanulate, with subregular, hexagonal pores, and five stout ribs.
The marginal distance between the two anterior (lateral) ribs is twice as
great as the distance between every two other ribs (the postero-lateral
ribs being basal branches of the antero-lateral ribs). Peristome with a
double corona of short, conical spines.
_Dimensions._--Cephalis 0.02 long, 0.04 broad; thorax 0.06 long, 0.17
broad.
_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.
5. _Sethophormis astrodiscus_, n. sp.
Cephalis small, flatly vaulted, cap-shaped with irregular polygonal pores.
Thorax very flatly vaulted, nearly discoidal, with subregular hexagonal
pores, and five stout ribs. The marginal distance between all five ribs is
nearly equal. Peristome denticulate with an elegant corona of small square
pores and short conical thorns.
_Dimensions._--Cephalis 0.015 long, 0.035 broad; thorax 0.05 long, 0.2
broad.
_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.
{1245}Subgenus 3. _Hexaphormis_, Haeckel, 1881, Prodromus, p. 432.
_Definition._--Thorax with six radial ribs (three primary perradial and
three secondary interradial beams).
6. _Sethophormis hexalactis_, n. sp. (Pl. 56, fig. 6).
Cephalis large, hemispherical, with irregular, polygonal pores. Thorax
flatly campanulate, with subregular, hexagonal pores, and six stout radial
ribs; the lateral connected in pairs. (Fig. 6 exhibits the central part of
the shell, seen from below.) In the subcircular collar septum the two
anterior (jugular) meshes are much smaller than the two posterior
(cardinal) meshes. The odd anterior (sternal) rib is opposite to the
posterior (caudal) rib. The two paired ribs of each side (antero-lateral or
pectoral and postero-lateral or ventral ribs) diverge from one common
point. In the specimen figured the left half of the thorax exhibited the
two regular ribs, and the right half three, a posterior accessory branch
being developed (transition to _Octophormis_). This specimen might indeed
be called _Heptaphormis heptalactis_.
_Dimensions._--Cephalis 0.02 long, 0.05 broad; thorax 0.08 long, 0.22
broad.
_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.
7. _Sethophormis hexagonalis_, n. sp.
Cephalis small, flat, cap-shaped, with small, regular, hexagonal pores.
Thorax flatly conical, nearly discoidal, with larger pores of the same
form, and six stout, straight, prominent ribs. These arise at equal
distances from the six corners of the hexagonal base of the collar septum.
Peristome hexagonal, with a corona of short spines.
_Dimensions._--Cephalis 0.015 long, 0.04 broad; thorax 0.06 long, 0.24
broad.
_Habitat._--North Atlantic, Station 354, surface.
Subgenus 4. _Octophormis_, Haeckel.
_Definition._--Thorax with eight radial ribs, four secondary interradial
beams being interpolated between the four primary perradial beams of
_Tetraphormis_.
8. _Sethophormis octalactis_, n. sp.
Cephalis large, hemispherical, with irregular, polygonal pores. Thorax
flatly campanulate, with regular, hexagonal pores, and eight stout,
regularly-disposed, radial ribs reaching the margin at equal distances.
Four of these correspond to the four primary ribs of _Tetraphormis
cruciata_, and exhibit at their base a larger pair of basal pores,
surrounded by a semicircular ring (Pl. 70, fig. 5); the other four are
secondary, interpolated. Peristome circular, simple.
_Dimensions._--Cephalis 0.03 long, 0.06 broad; thorax 0.1 long, 0.22 broad.
_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.
{1246}Subgenus 5. _Enneaphormis_, Haeckel, 1881, Prodromus, p. 432.
_Definition._--Thorax with nine radial ribs, three of which are the primary
beams, the other six being secondary and interpolated.
9. _Sethophormis rotula_, n. sp. (Pl. 57, fig. 9).
_Enneaphormis rotula_, Haeckel, 1881, Prodromus et Atlas, pl. lvii. fig.
9.
Cephalis very large, flat, cap-shaped, trilobed, with irregular, polygonal
network. Horizontal collar-ring stout, hexagonal, with three larger and
three alternate smaller sides of half the length. From the middle of the
three larger sides arise three horizontal, centripetal, radial beams, which
are united in the centre of the collar-septum--the three primary cortinar
beams. These are prolonged outside into three centrifugal primary ribs of
the thorax. From the six corners of the collar-ring arise six other
secondary, thoracic ribs, equal in size and similar in form to the three
primary. Each of these nine equal, straight ribs of the thorax is thickened
towards the distal end, and bears at equal distances five pairs of opposite
(tangential) lateral branches. The opposite branches of the neighbouring
spines become united, and lie nearly horizontally in one plane, so that the
flat, discoidal thorax is like a nine-angled wheel with nine equally
distant spokes and five concentric, nine-angled rings.
_Dimensions._--Cephalis 0.12 diameter, thorax 0.36 diameter.
_Habitat._--Central Pacific, Stations 270 to 274, depth 2350 to 2925
fathoms.
10. _Sethophormis triloba_, n. sp.
Cephalis large, hemispherical, distinctly trilobed, with dense, irregular,
polygonal network. From the centre of its top diverge three stout arches or
semilunar rods, which are curved downwards, and unite with the three
horizontal, radial beams of the collar-septum inside the collar-ring. These
three parietal arches of the cephalis are much stronger than in the similar
preceding species (Pl. 57, fig. 9), and between them are placed three
vaulted bosoms of the cephalis. The collar-ring and the thorax are of the
same form as in the preceding, but possess only four concentric,
nine-angled rings.
_Dimensions._--Cephalis 0.05 long, 0.08 broad; thorax 0.24 diameter.
_Habitat._--North Pacific, Station 244, depth 2900 fathoms.
11. _Sethophormis enneastrum_, n. sp.
Cephalis very large, flat, cap-shaped, with hexagonal base, trilobed, of
similar form and structure to the two preceding species. The flat,
discoidal thorax has also the same form, with nine stout ribs and five
concentric, nine-angled rings; its forty-five large meshes, however, are
not so simple {1247}as these (Pl. 57, fig. 9), but are subdivided into
irregular, smaller meshes by interpolated radial beams connecting the
concentric rings.
_Dimensions._--Cephalis 0.1 diameter, thorax 0.3 diameter.
_Habitat._--North Pacific, Station 253, depth 3125 fathoms.
12. _Sethophormis arachnium_, n. sp.
Cephalis very large, flat, cap-shaped, trilobed, with hexagonal base, of
the same structure as in the three preceding species. The flat discoidal
thorax is also similar, and has the same structure as in the preceding
species (Pl. 57, fig. 9); but the number of concentric, nine-angled rings
is raised from five to eight, and in its outer part nine secondary radial
beams are interpolated between the nine primaries, so that the peristome
has not nine but eighteen corners.
_Dimensions._--Cephalis 0.08 diameter, thorax 0.4 diameter.
_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.
13. _Sethophormis enneactis_, n. sp.
Cephalis small, hemispherical, with small, irregular, polygonal pores.
Thorax flatly pyramidal, nearly discoidal, with nine prominent, stout ribs,
which are connected by numerous (twelve to sixteen) horizontal, nine-angled
rings. In the outer half of the thorax there are nine weaker secondary ribs
interpolated between the nine stronger primaries, and eighteen shorter and
feebler tertiary ribs between the former and the latter. Peristome
denticulated, nine-angled.
_Dimensions._--Cephalis 0.03 diameter, thorax 0.08 long, 0.24 broad.
_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.
14. _Sethophormis eupilium_, n. sp. (Pl. 56, fig. 9).
Sethopyramis eupilium, Haeckel, 1882, Atlas, pl. lvi. fig. 9.
Craspedilium eupilium, Haeckel, 1878, Manuscript.
Cephalis very small, hemispherical, hyaline, without pores. Thorax flatly
pyramidal, with nine concave, triangular faces and nine little curved,
stout, radial beams. Between these are interpolated numerous incomplete
secondary beams, which are absent in the apical part of the thorax. The
radial beams being connected by numerous (thirty to forty or more)
horizontal, ring-like threads, a delicate arachnoidal network with small,
quadrangular pores is produced. Peristome nine-angled, with a peculiar
vertical gallery, composed of four horizontal, parallel, nine-angled rings,
which are connected by numerous vertical, parallel bars, therefore with
three transverse rows of square pores. This peculiar species is very
different from the preceding and may represent a separate genus,
_Craspedilium_.
_Dimensions._--Cephalis 0.01 diameter, thorax 0.1 long, 0.25 broad.
_Habitat._--Central Pacific, Station 271, surface.
{1248}Subgenus 6. _Astrophormis_, Haeckel.
_Definition._--Thorax with a variable number of radial ribs (twelve to
twenty or more).
15. _Sethophormis aurelia_, n. sp. (Pl. 55, figs. 3, 4).
_Leptarachnium aurelia_, Haeckel, 1879, Manuscript et Atlas.
Cephalis large, nearly hemispherical, with irregular, delicate network of
small square meshes. Collar-septum with four large meshes, separated by a
cross of four bars, opposite in pairs. Thorax flatly campanulate, with
delicate, subregular, hexagonal meshes, and twenty-four prominent radial
ribs; four of these are primary or perradial (centrifugal prolongations of
the four bars of the collar-septum); four others are interradial or
secondary, alternating with the former at angles of 45°; sixteen others are
adradial or tertiary, interpolated between the first and second more or
less irregularly. In some specimens the disposition of the twenty-four ribs
was more regular, in others more irregular, than in the specimen figured
(figs. 3, 4). The central capsule (fig. 4) exhibits a flat, cap-shaped part
with the nucleus (enclosed in the cephalis), and four large, pear-shaped
lobes protruded through the four large collar holes (somewhat deformed in
the preparation figured). The wall of the thorax exhibits at the base four
larger, nearly semicircular pores, bisected by the four primary thoracic
ribs. Peristome with twenty-four indentations (between the prominent distal
ends of the twenty-four ribs), often more distinct than in the specimen
figured.
_Dimensions._--Cephalis 0.03 long, 0.08 broad; thorax 0.1 to 0.2 long, 0.4
to 0.6 broad.
_Habitat._--Central Pacific, Station 263 to 274, depth 2350 to 2925
fathoms.
16. _Sethophormis dodecaster_, n. sp. (Pl. 56, fig. 12).
Cephalis small, flatly cap-shaped, with irregular, small, roundish pores.
Thorax flatly conical, nearly of the same shape as in the preceding
species, but only with twelve prominent ribs; four primary or perradial
ribs (as prolongations of the four crossed cortinar bars), and eight
adradial ribs interpolated between the former, and arising at some distance
from the collar ring. Peristome with twelve prominent pointed lobes
(supported by the distal ends of the twelve ribs), and with twelve
semicircular bosoms between them. (The specimen figured is young and not
fully developed.)
_Dimensions._--Cephalis 0.02 long, 0.04 broad; thorax 0.1 long, 0.3 broad.
_Habitat._--South Pacific, Station 298, depth 2225 fathoms.
17. _Sethophormis umbrella_, n. sp. (Pl. 70, figs. 4, 5).
Cephalis large, flatly cap-shaped, with irregular, small polygonal meshes.
Thorax flat, umbrella-shaped, with subregular, hexagonal meshes, and
sixteen strong radial ribs. Four of these are perradial, and centrifugal
prolongations of the four crossed collar beams; four others are
interradial, and {1249}arise, alternating with the former, directly from
the horizontal collar ring; eight ribs are adradial or tertiary, and arise
in pairs from the four large perradial basal arches of the thorax, which
become bisected by the four primary ribs. Peristome irregularly
denticulate.
_Dimensions._--Cephalis 0.02 long, 0.06 broad; thorax 0.12 long, 0.32
broad.
_Habitat._--North Pacific (off Japan), Stations 236 to 239, surface.
18. _Sethophormis floscula_, n. sp.
Cephalis small, hemispherical, with subregular, small hexagonal pores.
Thorax flatly conical, with larger hexagonal meshes and twenty-four ribs;
four of these are perradial and prolongations of the four collar bars; four
interradial arise from the collar ring between the former, alternating with
them. Each of these eight main ribs gives off two more or less irregular,
lateral branches (one at each side), altogether sixteen. The thorax is
similar to _Cladarachnium ramosum_ (Pl. 55, fig. 5), whilst the cephalis is
quite different. Peristome with twenty-four prominent triangular lobes.
_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.1 long, 0.4 broad.
_Habitat._--South Atlantic, Station 325, surface.
19. _Sethophormis leptoscenium_, n. sp.
Cephalis very small, spherical, with few small, circular pores. Thorax
flatly conical or tent-shaped, with concave lateral outlines, small
hexagonal meshes, and numerous (thirty to forty or more) strong, little
curved, simple radial ribs. Peristome nearly circular, with a corona of
small, irregular, conical spines.
_Dimensions._--Cephalis 0.015 diameter; thorax 0.07 long, 0.26 broad.
_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.
20. _Sethophormis leptopilium_, n. sp.
Cephalis very small, subspherical, hyaline, without pores. Thorax flatly
conical or hat-shaped, with concave lateral outlines, and a very delicate
network of small square meshes (similar to _Litharachnium araneosum_, Pl.
55, fig. 8). This is supported by thirty-two curved radial ribs, four of
which are primary, four secondary, and the other twenty-four interpolated.
Peristome horizontally expanded and little recurved, like the reflexed brim
of a hat.
_Dimensions._--Cephalis 0.12 diameter; thorax 0.08 long, 0.24 broad.
_Habitat._--South Pacific, Station 291, depth 2250 fathoms.
Genus 559. _Sethamphora_,[176] n. gen.
_Definition._--#Sethophormida# (vel Dicyrtida multiradiata aperta) with
numerous curved ribs in the wall of the ovate thorax, the small mouth of
which is constricted. Cephalis without horn.
{1250}The genus _Sethamphora_ differs from the preceding _Sethophormis_,
and from the next following ribbed Sethophormida, mainly in the small, more
or less constricted mouth; therefore the thorax is more or less ovate, and
its ribs curved, with the convexity external. Sethophormis may be divided
into two different subgenera, _Dictyoprora_ and _Cryptocephalus_; in the
former the cephalis is perfectly free and well developed, in the latter it
is more or less hidden in the uppermost part of the thorax (like
_Carpocanium_).
Subgenus 1. _Dictyoprona_, Haeckel, 1881, Prodromus, p. 430.
_Definition._--Cephalis large, perfectly free, not hidden in the thorax.
1. _Sethamphora hexapleura_, n. sp.
Shell ovate, smooth, with distinct collar stricture. Length of the two
joints = 3 : 11, breadth = 5 : 10. Cephalis large, free, hemispherical,
with small circular pores. Thorax truncate, ovate, with six strong curved
ribs, and six large triangular meshes between them in the upper half; five
smaller pores between every two ribs in the lower half (in three tiers);
therefore, together, thirty-six thoracic meshes. Mouth strongly
constricted, smooth, only one-third as broad as the thorax.
_Dimensions._--Cephalis 0.03 long, 0.05 broad; thorax, 0.11 long, 0.1
broad.
_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.
2. _Sethamphora enneapleura_, n. sp.
Shell subovate, smooth, with slight collar stricture. Length of the two
joints = 3 : 9, breadth = 4 : 8. Cephalis large, hemispherical, free, with
small circular pores. Thorax inflated, ovate, with nine strong curved ribs,
which are connected by five transverse circular rings at equal distances.
Forty-five rounded, squarish, large meshes between them, in five transverse
and nine longitudinal rows. Mouth constricted, smooth, half as broad as the
thorax.
_Dimensions._--Cephalis 0.03 long, 0.04 broad; thorax 0.09 long, 0.08
broad.
_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.
3. _Sethamphora dodecapleura_, n. sp.
Shell urceolate, smooth, with sharp collar stricture. Length of the two
joints = 3 : 9, breadth = 5 : 9. Cephalis flat, cap-shaped, free, with
twelve ribs, and very small pores between them. Thorax thick-walled,
inflated, with subcylindrical cavity, and twelve prominent sharp ribs,
alternating with twelve longitudinal rows of very small circular pores
(eight pores in each row). Mouth constricted, half as broad as the thorax.
_Dimensions._--Cephalis 0.03 long, 0.05 broad; thorax 0.09 long, 0.09
broad.
_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.
{1251}4. _Sethamphora mongolfieri_, Haeckel.
_Eucyrtidium mongolfieri_, Ehrenberg, 1854, Mikrogeol., Taf. xxxiv. fig.
18; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 72, Taf. x. fig. 3.
Shell urceolate, smooth, with distinct collar stricture. Length of the two
joints = 2 : 9, breadth = 3 : 7. Cephalis campanulate, with eighteen ribs
and small pores. Thorax nearly ellipsoidal, with eighteen prominent ribs,
and eighteen longitudinal rows of regular circular pores between them
(eight pores in each row; therefore 144 pores altogether). Mouth
constricted, only one-third as broad as the thorax.
_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.09 long, 0.07
broad.
_Habitat._--Fossil in Barbados.
5. _Sethamphora costata_, n. sp. Pl. 62, fig. 3.
Shell urceolate, smooth, very similar to the preceding species; also with
eighteen longitudinal ribs, but differing in the larger size of the
cephalis and its pores, and in the more slender and ovate form of the
thorax. Length of the two joints = 5 : 10, breadth = 5 : 8. Pores of the
cephalis more numerous. Mouth half as broad as the thorax.
_Dimensions._--Cephalis 0.05 long, 0.05 broad; thorax 0.1 long, 0.08 broad.
_Habitat._--Central Pacific, Stations 265 to 274, depth 2350 to 2925
fathoms.
6. _Sethamphora serrata_, n. sp.
Shell ovate, spinulate, without external collar stricture. Length of the
two joints = 1 : 6, breadth = 2 : 4. Cephalis flat, cap-shaped, with small
circular pores. Thorax ovate, truncate, with eighteen serrate longitudinal
ribs, alternating with eighteen longitudinal rows of short and broad rather
oblong pores (twenty to thirty pores in each row). Mouth strongly
constricted, only one-fourth as broad as the thorax.
_Dimensions._--Cephalis 0.02 long, 0.04 broad; thorax 0.12 long, 0.08
broad.
_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.
7. _Sethamphora ampulla_, Haeckel.
_Eucyrtidium ampulla_, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 15;
Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 72, Taf. x. figs. 11, 12.
Shell broad, urceolate, spiny, with sharp collar stricture. Length of the
two joints = 1 : 4, breadth = 1 : 5. Cephalis subspherical, with few small
pores (in figs. 12_a_ and 12_b_ of Ehrenberg, _loc. cit._, broken off, so
that the four pores of the cortinar septum appear). Thorax inflated,
bottle-shaped, with twenty prominent, sharply dentate ribs, alternating
with twenty longitudinal rows of circular pores (about eight pores in each
row). Mouth flat, constricted, one-third as broad as the thorax.
_Dimensions._--Cephalis 0.025 long, 0.03 broad; thorax 0.1 long, 0.14
broad.
_Habitat._--Fossil in Barbados.
{1252}8. _Sethamphora aërostatica_, Haeckel.
_Podocyrtis aërostatica_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 80, Taf. xvi. fig. 4.
Shell broad, urceolate, smooth, with sharp collar stricture. Length of the
two joints = 2 : 6, breadth = 3 : 8. Cephalis hemispherical, large, with
few pores (broken off in fig. 4_a_ of Ehrenberg, so that the six collar
pores appear). Thorax inflated, bottle-shaped, with twenty-two to
twenty-four smooth prominent ribs, alternating with the some number of
longitudinal rows of small circular pores. Mouth very small, strongly
constricted, scarcely as broad as the cephalis, with three short teeth.
_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.08
broad.
_Habitat._--Fossil in Barbados.
Subgenus 2. _Cryptocephalus_, Haeckel, 1881, Prodromus, p. 430.
_Definition._--Cephalis more or less hidden in thorax, being partly
enveloped by its uppermost part.
9. _Sethamphora microstoma_, n. sp. (Pl. 57, fig. 5).
_Cryptoprora microstoma_, Haeckel, Atlas, pl. lvii., fig. 5.
Shell ovate, smooth, without external collar stricture. Length of the two
joints = 1 : 6, breadth = 2 : 4. Cephalis flat, cap-shaped, without ribs,
with small circular pores. Thorax ovate, with twenty-four prominent ribs,
alternating with deep longitudinal furrows, each of which contains a series
of about fifteen small circular pores. Mouth very small, representing a
short cylindrical tube, which is only one-eighth as broad as the thorax.
_Dimensions._--Cephalis 0.02 long, 0.04 broad; thorax 0.12 long, 0.08
broad.
_Habitat._--Western Tropical Pacific, Station 220, depth 1100 fathoms.
10. _Sethamphora favosa_, n. sp, (Pl. 57, fig. 4).
_Cryptocephalus favosus_, Haeckel, 1881, Prodromus, p. 430.
Shell ovate, dimply. Length of the two joints = 1 : 5, breadth = 1 : 5.
Cephalis subspherical, small, completely hidden in the thickened top of the
thorax (but very distinct in the longitudinal section). Thorax ovate, with
twenty-five to thirty longitudinal ribs, alternating with the same number
of longitudinal furrows, each of which contains ten to twelve circular,
hexagonally framed pores. In the smooth wall of the peristome only twelve
triangular ribs are visible. Mouth constricted, one-third as broad as the
thorax.
_Dimensions._--Cephalis 0.02 diameter; thorax 0.1 long, 0.09 broad.
_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.
{1253}Genus 560. _Sethopyramis_,[177] Haeckel, 1881, Prodromus, p. 432
(sensu emendato !)
_Definition_.--#Sethophormida# (vel Dicyrtida multiradiata aperta) with
numerous straight or slightly curved radial ribs in the wall of the
pyramidal thorax. Network simple. Cephalis commonly without horn.
The genus _Sethopyramis_ and the four following genera form together a
peculiar small group (Sethopyramida), characterised by the slender
pyramidal shell, in the wall of which numerous (six to nine or more) radial
ribs are enclosed. These ribs may be regarded as the terminal feet of a
_Calpophæna_ or _Halicalyptra_, which become connected by transverse bars.
_Sethopyramis_ may be derived also directly from _Patagospyris_ by loss of
the primary sagittal ring and reduction of the cephalis.
Subgenus 1. _Sestropyramis_, Haeckel.
_Definition_.--Pyramidal shell with six radial main beams (sometimes also
five or seven, as individual varieties).
1. _Sethopyramis scalaris_, Haeckel.
_Cornutella scalaris_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 68, Taf. ii. fig. 1.
Shell smooth, slenderly pyramidal, hexagonal. Cephalis large, subglobular,
hyaline, without pores (or with very small and scarce pores). Thorax with
six straight (or little curved) stout longitudinal ribs or radial beams,
which are connected by twenty to thirty complete, hexagonal, horizontal
rings. The large meshes so produced are regular, square, their length and
breadth equally and gradually increasing towards the mouth.
_Dimensions_.--Cephalis 0.04 diameter; thorax (with twenty-four transverse
rings) 0.4 long, 0.15 broad at the mouth.
_Habitat_.--Fossil in Barbados.
2. _Sethopyramis hexalactis_, n. sp.
Shell thorny, of the same form as, and similar structure to, the preceding
species, but differing in the spiny surface and the smaller subglobular
cephalis, which bears small circular pores and an oblique conical horn
twice the length. The whole surface is covered with short conical thorns.
_Dimensions_.--Cephalis 0.02 diameter; thorax (with twenty transverse
rings) 0.25 long, 0.1 broad.
_Habitat_.--Central Pacific, Station 268, depth 2900 fathoms.
Subgenus 2. _Cephalopyramis_, Haeckel, 1881, Prodromus, p. 432.
_Definition._--Pyramidal shell with nine radial main beams (sometimes also
eight or ten, as individual varieties).
{1254}3. _Sethopyramis enneactis_, n. sp. (Pl. 56, fig. 7).
_Cephalopyramis enneactis_, Haeckel, 1881, Prodromus et Atlas, pl. lvi.
fig. 7.
Shell smooth, slender, pyramidal. Cephalis large, ovate, with pointed apex,
nearly hyaline, with very few and small scattered pores. Thorax very
slenderly pyramidal, with straight lateral outlines, and nine stout and
straight radial beams, which are connected by fifteen to twenty horizontal
complete rings. Meshes subregular, square, simple, without secondary
network; their length and breadth equally increasing towards the mouth.
_Dimensions._--Cephalis 0.05 long, 0.03 broad; thorax (with twenty
transverse rings) 0.24 long, 0.1 broad at the mouth.
_Habitat._--Central Pacific, Stations 265 to 268, depth 2700 to 2900
fathoms.
4. _Sethopyramis quadrata_, n. sp. (Pl. 54, fig. 2).
Shell smooth, slenderly pyramidal, very similar in form and structure to
the preceding species; differing from it in the rudimentary cephalis, which
is very small, hemispherical, with few small porules. The three internal
cortinar bars of the collar stricture are present; when they become lost
this species passes over into _Bathropyramis quadrata_ (Pl. 54, fig. 1).
_Dimensions._--Cephalis 0.01 long, 0.02 broad; thorax (with ten transverse
rings) 0.15 long, 0.1 broad at the mouth.
_Habitat._--North Pacific, Station 244, depth 2900 fathoms.
5. _Sethopyramis quadratella_, Haeckel.
_Cornutella quadratella_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 68, Taf. ii. fig. 2.
_Litharachnium quadratella_, Bütschli, 1882, Zeitschr. f. wiss. Zool.,
vol, xxxvi. p. 540, Taf. xxxiii. fig. 37.
Shell smooth, broadly pyramidal. Cephalis ovate, small, blunt, hyaline,
with very few and small pores (in the figure of Ehrenberg broken off).
Thorax broadly pyramidal, with straight lateral outlines, and nine stout
and straight radial beams, which are connected by eight to twelve
horizontal complete rings. Meshes in the upper half regular, square, in the
lower half broad, rectangular (in the tenth transverse row twice as broad
as long).
_Dimensions._--Cephalis 0.03 long, 0.02 broad; thorax (with ten transverse
rings) 0.15 long, 0.15 broad.
_Habitat._--Fossil in Barbados.
6. _Sethopyramis trapezoides_, n. sp.
Shell smooth, broadly pyramidal. Cephalis large, ovate, hyaline, without
pores; its collar septum exhibits distinctly the four collar pores (two
larger cardinal and two smaller jugular pores). {1255}Thorax broad,
pyramidal, with slightly concave lateral outlines and nine (sometimes eight
or ten) curved ribs, which are connected by eighteen to twenty-four
complete transverse rings. The large meshes, so produced, have the form of
a parallel trapezoid, and are in the eighth transverse row three times as
broad as long. (Differs from _Bathropyramis trapezoides_, Pl. 54, fig. 3,
mainly by the possession of a well developed cephalis).
_Dimensions._--Cephalis 0.04 long, 0.03 broad; thorax (with eighteen rings)
0.32 long, 0.24 broad.
_Habitat._--South Pacific, Station 285, depth 2375 fathoms.
7. _Sethopyramis spinosa_, n. sp.
Shell thorny, slender, pyramidal. Cephalis small, subspherical, with few
small pores and a straight, vertical, conical horn twice the length. Thorax
with nine straight ribs, which are connected by sixteen to twenty complete
transverse nine-angled rings. The large meshes so produced are subregular,
square. From each nodal point a short conical spine arises. (Differs from
the similar _Bathropyramis spinosa_, Pl. 54, fig. 4, by the development of
the cephalis and the simple pointed, unforked spines.)
_Dimensions._--Cephalis 0.03 diameter; thorax (with sixteen rings) 0.2
long, 0.12 broad.
_Habitat._--Central Pacific, Station 263, depth 2650 fathoms.
8. _Sethopyramis hexagonalis_, n. sp.
Shell papillate, slender, pyramidal. Cephalis small, hemispherical, with a
straight conical horn twice the length, and small circular pores. Thorax
conical, with slightly convex outlines and nine stout, somewhat curved ribs
in zig-zag form, which are connected by ten to twelve interrupted
transverse bars. From each nodal point a small conical papilla arises. The
large meshes so produced are regular, hexagonal, gradually increasing in
size towards the mouth.
_Dimensions._--Cephalis 0.03 diameter; thorax (with twelve transverse rows
of meshes) 0.18 long, 0.12 broad.
_Habitat._--South Atlantic, Station 335, depth 1425 fathoms.
9. _Sethopyramis cyclomma_, n. sp.
Shell thorny, slender, pyramidal. Cephalis large, subspherical, with
numerous very small circular pores, and a small conical horn of the same
length. Thorax similar in form and structure to that of the preceding
species; but each hexagonal mesh is provided with a very thin circular
hyaline ring (like a diaphragm), so that the openings are not hexagonal,
but circular. From each nodal point a short pointed conical or slightly
forked spine arises.
_Dimensions._--Cephalis 0.02 diameter; thorax (with ten transverse rows of
meshes) 0.18 long, 0.14 broad.
_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.
{1256}Subgenus 3. _Actinopyramis_, Haeckel.
_Definition._--Pyramidal shell with twelve or more radial beams (commonly
twelve to twenty-four, sometimes forty or more).
10. _Sethopyramis dodecalactis_, n. sp.
Shell smooth, slender, pyramidal. Cephalis small, spherical, hyaline, with
a short conical horn. Thorax with twelve radial ribs in the upper half,
between which twelve others are interpolated in the lower half. These are
connected by twenty to twenty-four complete transverse rings. The meshes so
produced are subregular, rectangular.
_Dimensions._--Cephalis 0.03 diameter; thorax 0.6 long, 0.2 broad.
_Habitat._--Indian Ocean, Madagascar (Rabbe), surface.
11. _Sethopyramis bicornis_, n. sp.
Shell spiny, slender, pyramidal. Cephalis small, spherical, hyaline, with
two divergent conical horns, the major (occipital) three times and the
minor (frontal) twice as long. Thorax slender, pyramidal, campanulate,
thorny, with twenty to thirty radial beams, which are little curved, convex
in the upper, concave in the lower half, and connected by numerous
interrupted transverse bars. Meshes in the upper third rounded, in the
lower two-thirds quadrangular, of very different sizes. Surface covered
with spinules.
_Dimensions._--Cephalis 0.02 diameter; thorns 0.9 long, 0.4 broad.
_Habitat._--North Pacific, Station 241, depth 2300 fathoms.
12. _Sethopyramis maxima_, n. sp.
Shell smooth, slender, pyramidal. Cephalis small, spherical, with few small
pores, and a stout, vertical, conical horn twice the length. Thorax very
prolonged, conical, with straight lateral outlines and numerous (twenty to
fifty) radial beams (in the upper third twelve, in the middle third
twenty-four, in the lower third forty to fifty, by interpolation); they are
connected by very numerous interrupted transverse bars. Meshes subregular,
quadrangular. Surface smooth.
_Dimensions._--Cephalis 0.02 diameter; thorax 1.05 long, 0.45 broad.
_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.
Genus 561. _Plectopyramis_,[178] Haeckel, 1881, Prodromus, p. 432.
_Definition._--#Sethophormida# (vel Dicyrtida multiradiata aperta) with
numerous straight or slightly curved radial ribs in the wall of the
pyramidal thorax. Network double, the large primary meshes being
fenestrated by fine secondary network. Cephalis commonly without horn.
{1257}The genus _Plectopyramis_ differs from the preceding _Sethopyramis_,
its ancestral form, only in the peculiar double fenestration of the shell,
the large primary meshes of which are separated by strong bars, and filled
up by a very delicate arachnoidal network, composed of small pores and very
thin threads between them. This double lattice-work often exhibits a very
remarkable regularity. As in the preceding genus, the number of radial ribs
is commonly six or nine, rarely twelve to twenty or more.
Subgenus 1. _Hexapleuris_, Haeckel.
_Definition._--Pyramidal shell with six radial main beams (sometimes five
or seven in individual varieties).
1. _Plectopyramis magnifica_, Haeckel.
_Polycystina magnifica_, Bury, 1862, Polycystins of Barbados, pl. xi.
fig.
Shell smooth, slender, pyramidal. Cephalis large, ovate, pointed, separated
from the thorax by a very deep collar stricture, with few irregular pores.
Thorax with six strong and straight radial beams, which are connected by
about twenty horizontal, hexagonal rings. The large meshes so produced are
regular, square, and filled up by an extremely delicate secondary
arachnoidal network, composed of regular square pores (as in Pl. 54, figs.
7, 8).
_Dimensions._--Cephalis 0.06 long, 0.04 broad; thorax (with twenty
transverse rings) 0.4 long, 0.12 broad.
_Habitat._--Fossil in Barbados.
2. _Plectopyramis hexapleura_, n. sp.
Shell thorny, slender, pyramidal. Cephalis large, ovate, blunt, with deep
collar stricture. Thorax with six strong and straight radial beams, which
are connected by numerous (twenty to thirty) interrupted transverse bars.
The large meshes so produced are irregular, quadrangular, and filled up by
irregular, delicate, secondary network, with small polygonal pores.
_Dimensions._--Cephalis 0.05 long, 0.03 broad; thorax 0.3 long, 0.1 broad.
_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.
Subgenus 2. _Enneapleuris_, Haeckel.
_Definition._--Pyramidal shell with nine radial main beams (sometimes eight
or ten in individual varieties).
{1258}3. _Plectopyramis dodecomma_, n. sp. (Pl. 54, fig. 6).
Shell smooth, slenderly pyramidal, with straight outlines. Cephalis
conical, obtuse, with thirty-six small square pores (in nine divergent
longitudinal rows, each of four pores). Collar septum (between cephalis and
thorax) with four distinct collar pores. Thorax pyramidal, with nine very
stout and straight angular radial beams, which are connected by ten to
fifteen broad horizontal nine-angled rings. Each of the large regular,
square meshes so produced contains a very delicate fenestration, with
twelve regular, square pores, separated by two transverse and three
longitudinal crossed threads. A very regular and remarkable structure.
_Dimensions._--Cephalis 0.03 long, 0.02 broad; thorax (with ten rings) 0.2
long, 0.15 broad.
_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.
4. _Plectopyramis quadratomma_, n. sp.
Shell smooth, slenderly pyramidal. Cephalis large, ovate, hyaline, with few
very small basal pores and deep collar stricture. Thorax pyramidal, with
straight outline, and nine very stout and straight radial beams, which are
connected by fifteen to twenty horizontal nine-angled rings. Each of the
large regular, square meshes so produced is filled up by a very delicate
arachnoidal network, with very numerous and small square pores (as in the
similar _Cinclopyramis infundibulum_, Pl. 54, fig. 7, which differs in the
loss of the cephalis).
_Dimensions._--Cephalis 0.05 long, 0.03 broad; thorax (with fifteen rings)
0.32 long, 0.2 broad.
_Habitat._--North Pacific, Station 244, depth 2900 fathoms.
5. _Plectopyramis trapezomma_, n. sp. (Pl. 54, fig. 8).
Shell smooth, broadly pyramidal, with concave lateral outlines. Cephalis
hemispherical, small, with numerous small, circular pores. Thorax
pyramidal, with nine stout, concavely curved radial beams, which are
connected by twelve to sixteen horizontal nine-angled rings. The large
meshes so produced are in the upper half square, in the lower half parallel
trapezoid (in the fifteenth ring three times as broad as long), and filled
up by a secondary arachnoidal network, with very numerous and small square
pores.
_Dimensions._--Cephalis 0.015 long, 0.025 broad; thorax (with fifteen
rings) 0.22 long, 0.2 broad.
_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.
6. _Plectopyramis polygonomma_, n. sp.
Shell smooth, pyramidal, very similar to the preceding species; differing
from it in the irregular shape of the delicate polygonal (not tetragonal)
secondary network, filling up the large rectangular meshes. The cephalis is
larger, hyaline, pear-shaped, pointed, without pores, with a deep collar
stricture. The nine radial beams of the thorax are less concave.
_Dimensions._--Cephalis 0.04 long, 0.03 broad; thorax (with fifteen rings)
0.3 long, 0.22 broad.
_Habitat._--South Pacific, Station 295, depth 1500 fathoms.
{1259}7. _Plectopyramis heteromma_, n. sp.
Shell smooth, slenderly pyramidal, with concave outlines. Cephalis very
small, subspherical, with a small oblique, conical horn, and very small,
scarce circular pores. Thorax with nine stout concavely curved radial
beams, which are connected by numerous (thirty to fifty or more)
interrupted transverse bars. The large irregular meshes so produced are
filled up by irregular, polygonal, delicate lattice-work.
_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax 0.6 long, 0.3 broad.
_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.
8. _Plectopyramis serrata_, n. sp.
Shell thorny, slenderly pyramidal, with straight outlines. Cephalis very
small, spherical, with a long oblique, conical horn, and very small
circular pores. Thorax with nine stout, straight, regularly serrate ribs or
radial beams, which are connected by numerous (twenty to thirty or more)
interrupted transverse bars. The latter, being crossed by intercalated and
interrupted irregular radial beams, produce a subregular secondary network
of rectangular meshes of different sizes.
_Dimensions._--Cephalis 0.02 long, 0.02 broad; thorax, 0.3 long, 0.2 broad.
_Habitat._--South Pacific, Station 298, depth 2225 fathoms.
9. _Plectopyramis fenestrata_, Haeckel.
_Pyramis fenestrata_, Bury, 1862, Polycystins of Barbados, pl. xxi. fig.
8.
Shell thorny, broadly pyramidal, with straight outlines. Cephalis very
small, spherical, hyaline. Thorax with nine stout, spinulate, straight ribs
or radial beams, which are connected by ten to fifteen transverse bars,
which in the upper half are complete rings, in the lower half interrupted,
and crossed by irregularly intercalated radial beams. Meshes therefore
irregular, quadrangular. All the bars are thorny.
_Dimensions._--Cephalis 0.01 diameter; thorax 0.2 long, 0.16 broad.
_Habitat._--Tropical Atlantic.
10. _Plectopyramis furcata_, n. sp.
Shell spiny, slenderly pyramidal, with straight outlines. Cephalis small,
spherical, with few small pores. Thorax with nine stout and straight
spinulate ribs, which are connected by a variable number of irregular
interrupted transverse bars; the large quadrangular meshes so produced are
filled up by irregular delicate network. The entire surface of the thorax
is covered with short forked spines.
_Dimensions._--Cephalis 0.02 diameter; thorax 0.3 long, 0.2 broad.
_Habitat._--Indian Ocean (Zanzibar), Pullen, depth 2200 fathoms.
{1260}Subgenus 3. _Polypleuris_, Haeckel.
_Definition._--Pyramidal shell with numerous (twelve or more) radial main
beams (commonly twelve to eighteen, sometimes twenty to thirty or more).
11. _Plectopyramis polypleura_, n. sp. (Pl. 56, fig. 8).
Shell smooth, slenderly conical, with straight outlines. Cephalis small,
subspherical, with very small dot-like pores, and an oblique conical horn
twice the length. Thorax with numerous (twenty to thirty) divergent
longitudinal ribs; usually twelve of these radial beams appear as stronger,
primary main ribs, and twelve to eighteen other as secondary, feebler,
interpolated ribs. They are crossed by numerous (twenty to forty or more)
horizontal rings. The large meshes so produced are quadrangular, and partly
filled up by a very delicate secondary network, with small square pores.
_Dimensions._--Cephalis 0.03 diameter; thorax 0.36 long, 0.24 broad.
_Habitat._--Central Pacific, Station 267, depth 2700 fathoms.
12. _Plectopyramis lagena_, n. sp.
Shell smooth, wine-bottle shaped, or slenderly conical-campanulate, with
bent outlines, which are concave in the upper, convex in the lower half.
Cephalis very small, spherical, hyaline, without pores. Thorax with
twenty-four radial ribs, twelve stronger primary, alternating with twelve
feebler secondary. They are crossed by interrupted transverse bars. The
irregular quadrangular meshes so produced are filled up by a delicate,
irregular, secondary network.
_Dimensions._--Cephalis 0.02 diameter; thorax 0.5 long, 0.3 broad.
_Habitat._--South Atlantic, Station 335, depth 1425 fathoms.
Genus 562. _Spongopyramis_,[179] n. sp.
_Definition._--#Sethophormida# (vel Dicyrtida multiradiata aperta) with
numerous straight or slightly curved radial ribs in the wall of the
pyramidal thorax. Network spongy. Cephalis commonly without horn.
The genus _Spongopyramis_ has arisen from _Sethopyramis_ by development of
an irregular spongy framework around the lattice-shell, and is one of the
small number of #Cyrtoidea# in which the shell-wall exhibits a spongy
structure. In both observed species the cephalis is small, but evident.
{1261}1. _Spongopyramis spongiosa_, n. sp. (Pl. 56, fig. 10).
_Plectopyramis spongiosa_, Haeckel, 1881, Prodromus et Atlas, _loc. cit._
Shell partly or entirely enveloped by spongy framework, slender, pyramidal,
with rather straight outlines. Cephalis very small, ovate, hyaline. Thorax
with nine very stout and nearly straight ribs, which are connected by
fifteen to twenty or more irregular, interrupted transverse bars. The
irregular quadrangular meshes so produced are filled up by an irregular
secondary network, with meshes of very different size and form. The dense
spongy envelope, which in the specimen figured covered only half the shell,
was complete in another older specimen.
_Dimensions._--Cephalis 0.015 long, 0.01 broad; thorax 0.4 long, 0.25
broad.
_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.
2. _Spongopyramis spongoplecta_, n. sp.
Shell entirely enveloped by spongy framework, pyramidal, with straight
outlines. Cephalis ovate (twice as large as in the preceding species), with
small circular pores. Thorax with twelve stout and straight ribs, which are
connected by twenty to twenty-five annular, transverse bars. The subregular
square meshes so produced are filled up by irregular, spongy network, which
envelops the whole shell more loosely than in _Spongopyramis spongiosa_.
_Dimensions._--Cephalis 0.03 long, 0.02 broad; thorax 0.5 long, 0.2 broad.
_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.
Genus 563. _Acanthocorys_,[180] Haeckel, 1881, Prodromus, p. 432.
_Definition._--#Sethophormida# (vel Dicyrtida multiradiata aperta) with
numerous radial ribs in the wall of the pyramidal thorax, prolonged into
divergent terminal feet. Network simple. Cephalis commonly with several
horns.
The genus _Acanthocorys_ and the following nearly allied _Arachnocorys_
possess a near relation to the three preceding pyramidal genera, but differ
from them in the terminal prolongation of the radial ribs, which are
commonly spiny and form a corona of free feet around the mouth of the
thorax. The cephalis is usually much larger than in the three preceding
genera, and bears a variable number of radial horns. Therefore these two
genera are probably older and nearer to the common ancestral form of the
Sethophormida than the preceding genera. It may be derived directly from
_Dictyophimus_ by interpolation of three secondary (interradial) ribs
between the three primary (perradial) ribs.
{1262}Subgenus 1. _Acanthocorallium_, Haeckel.
_Definition._--Thorax with six divergent ribs or radial beams (three
primary or perradial alternating with three secondary or interradial).
1. _Acanthocorys hexapodia_, n. sp.
Cephalis large, ovate, with subregular hexagonal pores, and six strong,
conical, simple, divergent horns of the same length. Thorax flat, conical,
smooth, with six large triangular basal holes, separated by six strong,
prismatic, smooth beams, which are connected only near the distal end by a
hexagonal ring of delicate, irregular network. Collar septum with three
meshes, separated by the three centripetal prolongations of the three
primary ribs.
_Dimensions._--Cephalis 0.05 long, 0.04 broad; thorax 0.12 long, 0.24
broad.
_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.
2. _Acanthocorys pristipodia_, n. sp.
Cephalis large, hemispherical, with irregular, polygonal pores, and
numerous (ten to twenty) bristle-shaped, radiating horns, which are conical
at the base, and twice as long. Thorax flatly campanulate, thorny, with six
strong, serrate or spinulate, divergent, radial ribs, prolonged into six
free conical feet of the same length. Meshes of the thorax irregular,
polygonal, a corona of six larger ones at the base. Collar septum with four
meshes, shaped as in Pl. 56, fig. 6.
_Dimensions._--Cephalis 0.04 long, 0.06 broad; thorax 0.08 long, 0.18
broad.
_Habitat._--North Pacific, Station 244, depth 2900 fathoms.
3. _Acanthocorys macropodia_, n. sp.
Cephalis small, subspherical, with irregular, roundish pores and numerous
small, bristle-shaped horns. Length of the two joints = 1 : 2, breadth =
1 : 6. Thorax sexangular, pyramidal, with six very long and straight,
widely divergent feet, which are prismatic and spiny, and three to five
times as long as the breadth of the shell. Only the upper third of the six
ribs is connected by irregular, roundish network, with six large triangular
holes at the base. Collar septum with four meshes which have the same
relation to the six ribs as in _Sethophormis hexalactis_ (Pl. 56, fig. 6).
_Dimensions._--Cephalis 0.025 diameter, thorax 0.05 long, 0.15 broad.
_Habitat._--Central Pacific, Station 271, surface.
4. _Acanthocorys bütschlii_, Haeckel.
? _Clathrocanium ehrenbergii_, Bütschli, 1882, Zeitschr. f. wiss. Zool.,
vol. xxxvi. pp. 514, 539, Taf. xxxii. fig. 18, _a_, _b_.
Cephalis large, subspherical, with numerous small, circular pores and three
to six divergent, slender, apical horns. Thorax flatly conical, smooth, not
much larger than the cephalis, with six {1263}large, triangular or ovate
basal holes between the six ribs. Three of these ribs are primary or
perradial, and arise immediately from the collar septum, alternating with
three secondary or interradial ribs, which arise more outside. The specimen
observed by me exhibited six apical horns, and was more complete than that
figured by Bütschli, the six ribs being prolonged over the connecting
lattice-girdle into six short, divergent feet.
_Dimensions._--Cephalis 0.06 long, 0.06 broad; thorax 0.08 long, 0.1 broad.
_Habitat._--Fossil in Barbados.
Subgenus 2. _Acanthocoronium_, Haeckel.
_Definition._--Thorax with nine divergent ribs or radial beams, three of
which are primary or perradial, the other six secondary or interradial.
5. _Acanthocorys umbellifera_, Haeckel.
_Arachnocorys umbellifera_, Haeckel, 1862, Monogr. d. Radiol., p. 305,
Taf. vi. fig. 12.
Cephalis large, ovate, with subregular, circular pores and numerous
divergent, simple spines of different lengths. Thorax flatly conical, with
nine strong, divergent ribs, which in the distal half are free, in the
proximal half connected by numerous transverse beams, forming irregular
polygonal meshes. Dorsal face of the thorax armed with scattered ascending
spines.
_Dimensions._--Cephalis 0.05 long, 0.035 broad; thorax 0.05 long, 0.12
broad.
_Habitat._--Mediterranean (Messina); Atlantic, Station 354, surface.
6. _Acanthocorys triloba_, n. sp.
Cephalis large, campanulate, trilobed, with irregular, roundish pores,
numerous spines, and a large pyramidal horn on the top, which is connected
by three constricted arches with the base of the horizontal collar beams.
From the latter arise as centrifugal prolongations three stout, curved,
primary ribs of the flatly vaulted thorax, and each of these gives off at
the base two opposite, lateral, secondary ribs. These nine ribs are spiny,
and connected by irregular, arachnoidal network.
_Dimensions._--Cephalis 0.05 long, 0.07 broad; thorax 0.08 long, 0.18
broad.
_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.
7. _Acanthocorys enneapodia_, n. sp.
Cephalis large, ovate, with irregular roundish pores, and numerous
divergent, ascending spines. Thorax smooth, conical, little larger, with
the same network, and nine larger, triangular holes at the base; with nine
straight, equally-disposed ribs, which are prolonged into slender feet
twice the length. With these latter alternate nine shorter radial spines,
arising from the truncate peristome.
_Dimensions._--Cephalis 0.05 long, 0.04 broad; thorax 0.05 long, 0.09
broad.
_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.
{1264}8. _Acanthocorys macroceras_, n. sp. (Pl. 97, fig. 12).
Cephalis large, hemispherical, spiny, with regular, circular pores, and a
very large, cylindrical, vertical horn five times as long as the whole
shell. Thorax spiny, campanulate, with irregular, roundish pores and nine
strong, curved ribs, prolonged into nine slender, divergent feet twice the
length, which are curved, convex in the proximal half and concave in the
distal half.
_Dimensions._--Cephalis 0.05 long, 0.08 broad; thorax 0.12 long, 0.2 broad.
_Habitat._--South Pacific, Station 298, depth 2225 fathoms.
9. _Acanthocorys furcata_, n. sp.
Cephalis large, subspherical, spiny, with irregular, roundish pores. Thorax
flatly conical, thorny, with irregular, polygonal pores, decreasing in size
toward the mouth, and with nine straight divergent ribs, which at the
peristome are forked and prolonged into eighteen slender, very long,
bristle-shaped feet.
_Dimensions._--Cephalis 0.045 diameter, thorax 0.07 long, 0.13 broad.
_Habitat._--South Atlantic, Station 323, depth 1900 fathoms.
Subgenus 3. _Acanthocorythium_, Haeckel.
_Definition._--Thorax with a variable number (ten to twenty or more) radial
ribs, prolonged into free terminal feet.
10. _Acanthocorys dodecaster_, n. sp.
Cephalis small, subspherical, with small circular pores and a large conical
horn of twice the length, and some accessory spines. Thorax thorny, flatly
campanulate, with twelve stout curved ribs, which at the peristome are
prolonged into twelve slender, curved feet of twice the length; four of
them are centrifugal prolongations of the four cortinar beams separating
the four large meshes of the collar septum; eight other ribs are secondary,
interpolated in pairs between the former. At the base of the thorax are
twelve large triangular holes between the ribs; the other network is
irregular, with polygonal meshes.
_Dimensions._--Cephalis 0.03 diameter, thorax 0.05 long, 0.12 broad.
_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.
11. _Acanthocorys polypodia_, n. sp.
Cephalis small, hemispherical, with small, roundish pores and divergent
radial spines. Thorax flatly conical, spiny, with twenty to twenty-four
divergent, straight ribs, which in the proximal {1265}third are separated
by the same number of large, triangular meshes, in the middle third
connected by irregular network, in the distal third free.
_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.15
broad.
_Habitat._--Central Pacific, Station 273, depth 2350 fathoms.
Genus 564. _Arachnocorys_,[181] Haeckel, 1860, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 837.
_Definition._--#Sethophormida# (vel Dicyrtida multiradiata aperta) with
numerous radial ribs in the wall of the pyramidal thorax, prolonged into
divergent terminal feet. Network double, with an arachnoidal outer mantle
around the inner lattice-shell. Cephalis commonly with numerous horns.
The genus _Arachnocorys_ has been derived from the preceding
_Acanthocorys_, by development of numerous external siliceous threads which
connect the radial horns of the cephalis with the secondary spines arising
from the thoracic ribs. In this way there becomes formed an outer
arachnoidal framework, enveloping loosely, like a delicate mantle, the
inner primary lattice-shell.
Subgenus 1. _Arachnocorallium_, Haeckel.
_Definition._--Thorax with six divergent ribs or radial beams (three
primary or perradial, alternating with three secondary or interradial).
1. _Arachnocorys hexaptera_, n. sp.
_Arachnocorys circumtexta_ (juv.?), R. Hertwig, 1879, Organism. d.
Radiol., p. 79, Taf. viii. fig. 2_a_.
Cephalis large, subspherical, with irregular, polygonal pores, and numerous
bristle-shaped spines twice the length; on the centre of the top a single
larger vertical horn. Thorax flatly conical, with six strong and straight
widely divergent ribs, which in the proximal half are separated by six
large holes, in the distal half connected by a broad ring of irregular
network. From each rib arises a perpendicular branch, and these branches
are connected together, and with the spines of the cephalis, by arachnoidal
network.
_Dimensions._--Cephalis 0.04 diameter, thorax 0.08 long, 0.24 broad.
_Habitat._--Central Pacific, Station 266; Mediterranean, surface.
2. _Arachnocorys discoides_, n. sp.
Cephalis small, pyramidal, with irregular, roundish pores and numerous thin
spines, on the top a single larger vertical horn. Thorax very flat, nearly
discoidal, with six strong and straight ribs, {1266}which by communication
of few larger and numerous smaller branches form an irregular network with
polygonal meshes. From each of the six ribs arise two or three larger,
perpendicular branches of half the length, and from the network numerous
smaller spines. All these dorsal spines of the shell are connected by a
dense arachnoidal wicker-work.
_Dimensions._--Cephalis 0.02 diameter, thorax 0.04 long, 0.3 broad.
_Habitat._--Central Pacific, Station 271, surface.
Subgenus 2. _Arachnocoronium_, Haeckel.
_Definition._--Thorax with nine divergent ribs or radial beams, three of
which are primary or perradial, the other six secondary or interradial.
(Sometimes eight or ten occur instead of the nine normal ribs.)
3. _Arachnocorys circumtexta_, Haeckel.
_Arachnocorys circumtexta_, Haeckel, 1862, Monogr. d. Radiol., p. 304,
Taf. vi. figs. 9-11.
_Arachnocorys circumtexta_, R. Hertwig, 1879, Organism. d. Radiol., p.
78, Taf. viii. fig. 2.
Cephalis large, subspherical, with numerous roundish pores, and eight to
ten slender, conical horns twice the length. Thorax flatly conical, with
nine strong, straight, widely divergent, conical feet, each of which bears
in the middle of its outer side a perpendicular ascending branch of half
the length. These branches and the horns of the cephalis are connected by
very thin, parallel, arachnoidal threads. Network of the thorax irregular,
with nine larger triangular holes at the base. Collar septum with numerous,
irregular, roundish pores.
_Dimensions._--Cephalis 0.04 to 0.05 diameter, thorax 0.08 to 0.12 long,
0.15 to 0.25 broad.
_Habitat._--Mediterranean (Messina); Atlantic, Stations 347 to 354,
surface.
4. _Arachnocorys enneaptera_, n. sp.
Cephalis large, campanulate, with irregular, polygonal pores, two larger
stout pyramidal and numerous slender, bristle-shaped horns. Thorax of the
same structure as in the preceding species, only the nine basal holes are
of twice the size; the lower network denser (as in _Clathrocanium diadema_,
Pl. 64, fig. 2). Collar septum with numerous, irregular, roundish pores.
_Dimensions._--Cephalis 0.05 diameter, thorax 0.12 long, 0.22 broad.
_Habitat._--Tropical Atlantic, Station 338, surface.
5. _Arachnocorys araneosa_, n. sp. (Pl. 56, fig. 11).
Cephalis large, subspherical, with circular, subregular, hexagonally framed
pores, and twenty to thirty slender, cylindrical, straight radial spines.
Thorax flatly conical, nearly of the same shape as in the two preceding
species, but with nine longer ribs, and more irregular, broader network
between them. From the middle of each rib arises, nearly horizontally, a
strong branch, which is directed {1267}outwards. These branches are
connected with the spines of the cephalis as well as with the distal half
of the ribs, by dense and delicate arachnoidal network, composed of
parallel, very thin, siliceous threads (in fig. 11 only partially
represented). Collar septum with numerous irregular, roundish pores.
_Dimensions._--Cephalis 0.04 diameter, thorax 0.1 long, 0.2 broad.
_Habitat._--Central Pacific, Station 270 to 274, surface.
6. _Arachnocorys arachnodiscus_, n. sp.
Cephalis small, campanulate, conical, with a single very large conical
central horn, and numerous smaller accessory spines. Thorax in form and
structure similar to that of the three preceding species, but much flatter,
being nearly discoidal. The meshes of the network are smaller and more
numerous, irregularly polygonal, and the nine basal holes little larger.
Collar septum with four large meshes (as in Pl. 60, fig. 6).
_Dimensions._--Cephalis 0.25 long, 0.3 broad; thorax 0.04 long, 0.24 broad.
_Habitat._--North Pacific, Station 248, surface.
7. _Arachnocorys trifida_, n. sp.
Cephalis large, campanulate, with irregular, roundish pores and numerous
ramified spines; in the centre of the top a larger pyramidal oblique horn
of twice the length. Thorax cap-shaped, flatly vaulted, with nine strong
convex ribs, prolonged into slender free feet. Three of these nine ribs are
the centrifugal prolongations of the three cortinar bars (united in the
centre of the collar stricture, separating its three large cortinar
meshes); the other six are diverging lateral branches of the former,
arising in pairs at both sides of its base. All nine ribs are connected by
delicate arachnoidal network with irregular polygonal meshes. From its
surface arise thin bristles, and from the base of each main rib a stout,
perpendicular branch. All these dorsal spines are connected by irregular,
arachnoidal wicker-work, covering thorax and cephalis. (A remarkable
primitive species?)
_Dimensions._--Cephalis 0.05 long, 0.06 broad; thorax 0.07 long, 0.18
broad.
_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.
Subgenus 3. _Arachnocorythium_, Haeckel.
_Definition._--Thorax with a variable number of radial ribs (twelve to
twenty or more), prolonged into free terminal feet.
8. _Arachnocorys polyptera_, n. sp.
Cephalis large, subspherical, with irregular, roundish pores and numerous
radial spines. Thorax flatly conical, with numerous radial ribs (twenty to
thirty), which are in the distal half free, in the proximal half connected
by delicate arachnoidal wicker-work, with polygonal, irregular meshes. From
its dorsal face arise numerous radial spines, which are connected together,
and with the cephalic spines, by very thin and numerous threads, parallel
between every two spines. Similar to {1268}_Arachnocorys araneosa_ (Pl. 56,
fig. 11), but differing in the structure of the cephalis, and in the
greater number of the ribs and spines.
_Dimensions._--Cephalis 0.04 diameter, thorax 0.12 long, 0.24 broad.
_Habitat._--South Pacific, Station 300, depth 1375 fathoms.
Genus 565. _Anthocyrtoma_,[182] n. gen.
_Definition._--#Sethophormida# (vel Dicyrtida multiradiata aperta) without
thoracic ribs, with six terminal feet around the mouth. Cephalis free, with
an apical horn.
The genus _Anthocyrtoma_ and the four following genera form together the
peculiar group of Carpocanida, comprising all those Sethophormida in which
the original thoracic ribs are lost, and only the terminal feet remain.
_Anthocyrtoma_ is the simplest form of this group, possessing only six
terminal feet, three primary perradial, and three alternating, secondary,
interradial. It may be directly derived either from _Lychnocanium_, by
interpolation of three interradial feet, or from _Hexaspyris_ by loss of
the sagittal ring.
1. _Anthocyrtoma serrulata_, Haeckel.
_Anthocyrtis serrulata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 66, Taf. vi. fig. 7.
Shell pear-shaped, rough, with obliterated collar stricture. Length of the
two joints = 1 : 4, breadth = 1 : 3. Cephalis ovate, with very small pores,
and a stout conical horn of the same length. Abdomen inflated, truncate,
with larger, regular, circular pores, twice as broad as the constricted
mouth. Six feet vertical, parallel, serrate, all of the same size, about as
long as the cephalis.
_Dimensions._--Cephalis 0.06 long, 0.05 broad; thorax 0.2 long, 0.17 broad.
_Habitat._--Fossil in Barbados.
2. _Anthocyrtoma alterna_, n. sp.
Shell pear-shaped, smooth, with distinct collar stricture. Length of the
two joints = 1 : 5, breadth = 1 : 6. Cephalis hemispherical, with a slender
conical horn of twice the length. Abdomen inflated, subglobular, with
regular, circular, hexagonally framed pores, three times as broad as the
narrow, constricted mouth. Six feet conical, smooth, somewhat divergent,
alternating, of different sizes; the three larger (perradial) half as long
as the shell, and twice as long as the three smaller (interradial).
(Similar to _Anthocyrtis ventricosa_.)
_Dimensions._--Cephalis 0.03 long, 0.04 broad; thorax 0.15 long, 0.18
broad.
_Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms.
{1269}Genus 566. _Anthocyrtis_,[183] Ehrenberg, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, 1847, p. 54.
_Definition._--#Sethophormida# (vel Dicyrtida multiradiata aperta) without
thoracic ribs, with nine terminal feet around the mouth. Cephalis free,
with an apical horn.
The genus _Anthocyrtis_ (in the original definition of Ehrenberg) contained
all Dicyrtida without thoracic ribs, with terminal feet. We here restrict
the definition to those Sethophormida in which the number of free terminal
feet is constantly nine (three primary perradial and three alternate pairs
of secondary interradial feet). _Anthocyrtis_ may be derived either
directly from _Patagospyris_ by loss of the sagittal ring, or from
_Lychnocanium_ by interpolation of three secondary feet.
Subgenus 1. _Anthocyrtella_, Haeckel.
_Definition._--Feet of the peristome-corona divergent, their basal distance
less than their terminal distance.
1. _Anthocyrtis mespilus_, Ehrenberg.
_Anthocyrtis mespilus_, Ehrenberg, 1854, Taf. xxxvi. fig. 13; Abhandl. d.
k. Akad. d. Wiss. Berlin, 1875, p. 66, Taf. vi. fig. 4 (not 5).
Shell smooth, with distinct collar stricture. Length of the two joints =
1 : 5, breadth = 2 : 6. Cephalis hemispherical, with a stout pyramidal horn
of twice the length. Thorax nearly hemispherical, with regular, circular,
quincuncial pores. Mouth scarcely constricted, with nine divergent,
triangular, lamellar feet, about as long as the thorax.
_Dimensions._--Cephalis 0.012 long, 0.02 broad; thorax 0.05 long, 0.06
broad.
_Habitat._--Fossil in Barbados.
2. _Anthocyrtis furcata_, Ehrenberg.
_Anthocyrtis furcata_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 64, Taf. vi. fig. 2.
Shell smooth, with deep collar stricture. Length of the two joints = 1 : 5,
breadth = 2 : 6. Cephalis hemispherical, with a short pyramidal horn of
half the length. Thorax hemispherical, with large, irregular, roundish
pores. Mouth scarcely constricted, with nine divergent, curved, slender
feet, which are about as long as the shell, and forked at the distal end.
_Dimensions._--Cephalis 0.01 long, 0.02 broad; thorax 0.05 long, 0.06
broad.
_Habitat._--Fossil in Barbados.
{1270}3. _Anthocyrtis butomus_, n. sp.
Shell thorny, with obliterated collar stricture. Length of the two joints =
2 : 6, breadth = 2 : 7. Cephalis ovate, with very small and scarce pores,
and a conical horn of the same length. Thorax inflated, pear-shaped, with
regular, circular, quincuncial pores. Mouth about half as broad,
constricted, with nine divergent, broad, nearly square, lamellar feet, half
as long as the thorax (similar to _Anthocyrtis serrulata_, Ehrenberg, _loc.
cit._, Taf. vi. fig. 7).
_Dimensions._--Cephalis 0.05 long, 0.04 broad; thorax 0.12 long, 0.14
broad.
_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.
4. _Anthocyrtis ventricosa_, Ehrenberg.
_Anthocyrtis ventricosa_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 66, Taf. viii. fig. 1.
Shell thorny, with obliterated collar stricture. Length of the two joints =
1 : 7, breadth = 2 : 7. Cephalis hemispherical, hyaline, without pores,
with a slender, conical horn, of about the same length. Thorax inflated,
pear-shaped or subspherical, with regular, circular, quincuncial pores.
Mouth only one-third as broad, much constricted, with nine divergent,
slender, conical feet, about one-fifth as long as the diameter of the shell
(partly broken off in Ehrenberg's figure).
_Dimensions._--Cephalis 0.03 long, 0.04 broad; thorax 0.14 long, 0.14
broad.
_Habitat._--Tropical Atlantic, Station 338, depth 1990 fathoms; also fossil
in Barbados.
Subgenus 2. _Anthocyrtissa_, Haeckel.
_Definition._--Feet of the peristome-corona parallel, vertical; their basal
and terminal distances equal.
5. _Anthocyrtis ophirensis_, Ehrenberg.
_Anthocyrtis ophirensis_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 285, Taf. ix. fig. 13.
Shell smooth, with slight collar stricture. Length of the two joints =
2 : 4, breadth = 1 : 5. Cephalis ovate, with irregular, roundish pores, and
a pyramidal, excentric, vertical horn of the same length. Thorax
campanulate, with delicate network of large, regular, hexagonal pores.
Mouth scarcely constricted, with nine parallel, vertical, conical feet,
about as long as the cephalis. (In the specimen figured by Ehrenberg only
seven feet are represented, two being broken off; two other specimens of
this species, captured by Rabbe, exhibited nine regularly disposed feet.)
_Dimensions._--Cephalis 0.03 long, 0.02 broad; thorax 0.08 long, 0.1 broad.
_Habitat._--Indian Ocean, Zanzibar (Pullen); Madagascar (Rabbe), surface.
{1271}6. _Anthocyrtis lauranthus_, n. sp.
Shell smooth with slight collar stricture. Length of the two joints =
1 : 3, breadth = 1 : 4. Cephalis ovate, with large, roundish pores, and a
conical horn of twice the length. Thorax inflated, campanulate, with
regular, circular, hexagonally framed pores. Mouth two-thirds as broad,
little constricted, with nine parallel, vertical, broad, lamellar,
triangular feet, half as long as the cephalis.
_Dimensions._--Cephalis 0.04 long, 0.03 broad; thorax 0.1 long, 0.12 broad.
_Habitat._--Central Pacific, Station 266 to 270, depth 2550 to 2925
fathoms.
7. _Anthocyrtis grossularia_, Ehrenberg.
_Anthocyrtis grossularia_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 64, Taf. vi. fig. 6.
Shell spiny, with deep collar stricture. Length of the two joints = 1 : 5,
breadth = 1 : 4. Cephalis subspherical, thorny, with a conical horn of the
same length. Thorax ovate, spiny, with numerous densely-crowded,
subregular, circular pores. Mouth about half as broad, constricted, with
nine parallel, vertical, slender, conical feet, about as long as the
cephalis.
_Dimensions._--Cephalis 0.04 long, 0.05 broad; thorax 0.2 long, 0.18 broad.
_Habitat._--Fossil in Barbados.
8. _Anthocyrtis subglobosa_, n. sp.
Shell spiny, with deep collar stricture. Length of the two joints = 1 : 7,
breadth = 1 : 7. Cephalis subspherical, with a conical horn twice the
length. Thorax nearly spherical, with small and very numerous, regular,
circular pores. Mouth only one-third as broad, constricted, with nine
parallel, vertical, square, lamellar feet, about twice as long as the
cephalis.
_Dimensions._--Cephalis 0.03 long, 0.035 broad; thorax 0.2 long, 0.2 broad.
_Habitat._--South Pacific, Station 297, depth 1775 fathoms.
Subgenus 3. _Anthocyrtura_, Haeckel.
_Definition._--Feet of the peristome-corona convergent, their basal
distance greater than their terminal distance.
9. _Anthocyrtis enneaphylla_, n. sp.
Shell smooth, with sharp collar stricture. Length of the two joints =
1 : 6, breadth = 1 : 5. Cephalis subspherical, with a conical horn twice
the length, nearly hyaline, with very small and scarce pores. Thorax nearly
spherical, with regular, circular, quincuncial pores. Mouth only {1272}half
as broad, with nine broad, triangular feet, twice as long as the cephalis,
and curved inwards, convergent towards the main axis.
_Dimensions._--Cephalis 0.02 long, 0.025 broad; thorax 0.11 long, 0.12
broad.
_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.
10. _Anthocyrtis ovata_, n. sp. (Pl. 62, fig. 13).
Shell smooth, with slight collar stricture. Length of the two joints =
1 : 5, breadth = 1 : 3. Cephalis ovate, with numerous small pores, and an
excentric conical horn of the same length. Thorax ovate, with regular,
circular, quincuncial pores. Mouth nearly of the same breadth, scarcely
constricted, with nine triangular, widely-separated feet, about as long as
the cephalis, and convergent towards the main axis.
_Dimensions._--Cephalis 0.035 long, 0.03 broad; thorax 0.15 long, 0.1
broad.
_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.
Genus 567. _Anthocyrtium_,[184] n. gen.
_Definition._--#Sethophormida# (vel Dicyrtida multiradiata aperta) without
thoracic ribs, with numerous terminal feet around the mouth (twelve to
fifteen or more). Cephalis free, with an apical horn.
The genus _Anthocyrtium_ has been derived from the two preceding genera by
further multiplication of the terminal feet, the number of which is at
least twelve to fifteen, often twenty or more. It may be that some species
have arisen directly from _Patagospyris_ by loss of the sagittal ring.
Subgenus 1. _Anthocyrtarium_, Haeckel.
_Definition._--Feet of the peristome-corona divergent, their basal distance
less than their terminal distance.
1. _Anthocyrtium chrysanthemum_, n. sp. (Pl. 62, fig. 14).
Shell smooth, with distinct collar stricture. Length of the two joints =
3 : 7, breadth = 4 : 9. Cephalis hemispherical, with small, circular pores,
and a large, straight, cylindro-conical horn, about as long as the shell.
Thorax campanulate, hemispherical, with six to eight transverse rows of
squarish pores, increasing in size downwards. Mouth little constricted,
with twelve to fifteen divergent, curved, slender feet, about as long as
the thorax.
_Dimensions._--Cephalis 0.03 long, 0.04 broad; thorax 0.07 long, 0.09
broad.
_Habitat._--Central Pacific, Station 270 to 274, depth 2350 to 2925
fathoms.
{1273}2. _Anthocyrtium centaurea_, Haeckel.
_Anthocyrtis mespilus_, var. _major_, Ehrenberg, 1875, Abhandl. d. k.
Akad. d. Wiss. Berlin, p. 66, Taf. vi. fig. 5.
Shell smooth, with sharp collar stricture. Length of the two joints =
2 : 6, breadth = 3 : 7. Cephalis hemispherical, with irregular, roundish
pores, and a very large pyramidal horn, longer than the shell, with
contorted edges. Thorax hemispherical, with six to eight transverse rows of
regular, circular pores of equal size. Mouth little constricted, with
fifteen to twenty divergent, curved, slender feet, about as long as the
shell.
_Dimensions._--Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.07
broad.
_Habitat._--Fossil in Barbados.
3. _Anthocyrtium anthemis_, n. sp.