breadth as the bars; eight to ten on the radius. Radial proportion of the
three spheres = 1 : 2 : 8. Surface covered with short conical by-spines
about twenty strong main spines, three-sided pyramidal, one-third as long
as the shell diameter.
_Dimensions._--Diameter of the outer shell 0.16, middle 0.04, inner 0.02;
cortical pores and bars 0.003; length of the main spines 0.05, basal
breadth 0.013.
_Habitat._--Fossil in the Tertiary rocks of Sicily and Barbados; living in
the Atlantic, Station 332, depth 2200 fathoms.
4. _Echinomma diadema_, n. sp.
Cortical shell thick walled with regular circular pores, twice as broad as
the bars; sixteen to eighteen on the radius. Radial proportion of the three
spheres = 1 : 3 : 11. Surface covered with short bristle-shaped by-spines
one third as long as the twelve stout conical main spines, which reach in
length the radius, and lie opposite in pairs in six axes.
_Dimensions._--Diameter of the outer shell 0.22, middle 0.06, inner 0.02;
cortical pores 0.006, bars 0.003 length of the main spines 0.12, basal
breadth 0.02.
_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.
Subgenus 2. _Echinommura_, Haeckel.
_Definition._--Pores of the cortical shell irregular, of different size or
form.
5. _Echinomma sphærechinus_, n. sp. (Pl. 29, fig. 2).
_Actinomma sphærechinus_, Haeckel, 1879, Atlas (pl. xxix. fig. 2).
Cortical shell thin walled, with irregular, roundish pores, twice to five
times as broad as the bars; five to seven on the radius. Both medullary
shells with regular, circular pores, twice as broad as the bars. Radial
proportion of the three spheres = 1 : 2 : 4. Surface covered with thirty to
fifty pyramidal main spines, as long as the diameter of the inner shell,
and with numerous small conical by-spines of half the length.
_Dimensions._--Diameter of the outer shell 0.11, middle 0.05, inner 0.025;
cortical pores 0.01 to 0.02, bars 0.004; length of the main spines 0.03,
basal breadth 0.005.
_Habitat._--North Atlantic, Station 353, surface.
6. _Echinomma trinacrium_, Haeckel.
_Actinomma trinacrium_, Haeckel, 1862, Monogr. d. Radiol., p. 441, Taf.
xxiv. figs. 6-8.
Cortical shell thin walled, with irregular, roundish pores, twice to three
times as broad as the bars. Both medullary shells with regular, circular
pores. Radial proportion of the three spheres {259}= 1 : 3 : 9. On the
surface about twenty three-sided pyramidal main spines, as long as the
radius, and numerous (forty to sixty) by-spines of half the length.
(Compare with this species _Actinomma trinacrium_, with which it is
connected by transitional forms.)
_Dimensions._--Diameter of the outer shell 0.09, middle 0.03, inner 0.01;
cortical pores 0.008 to 0.012, bars 0.004; length of the spines 0.02 to
0.05, basal breadth 0.01.
_Habitat._--Mediterranean (Messina).
7. _Echinomma toxopneustes_, n. sp. (Pl. 29, fig. 1).
Cortical shell thin walled, with large, irregular roundish, polygonally
framed pores, twice to four times as broad as the crested bars. Both
medullary shells of similar structure. Radial proportion of the three
spheres = 1 : 2.5 : 6. Numerous (thirty to fifty or more) thin radial beams
connecting them, prolonged outside into strong three-sided pyramidal
spines, shorter than the radius; each of the three wings with two teeth.
Between these, numerous smaller angular by-spines of one-quarter to
one-half the length.
_Dimensions._--Diameter of the outer shell 0.12, middle 0.05, inner 0.02;
cortical pores 0.01 to 0.03, bars 0.008; length of the main spines 0.05,
basal breadth 0.01.
_Habitat._--South-east Pacific (South of Juan Fernandez), Station 300,
surface.
Genus 103. _Pityomma_,[139] Haeckel, 1881, Prodromus, p. 453.
_Definition._--#Astrosphærida# with three concentric lattice-shells and
numerous branched radial spines.
The genus _Pityomma_ differs from its ancestral form, _Actinomma_, in the
ramification of its radial spines, and exhibits therefore the same relation
to it that _Elatomma_, among the Haliommida, bears to _Haliomma_.
1. _Pityomma scoparium_, n. sp.
Cortical shell thick walled, connected with both concentric medullary
shells by twenty thin radial beams, which are prolonged outside into twenty
large cylindrical radial spines; these are somewhat shorter than the shell
radius, simple in the proximal inner half, irregularly branched in the
outer half. All three spheres with regular, circular pores, twice to three
times as broad as the bars; radial proportion = 1 : 2 : 6. (Similar to
_Cladococcus scoparius_, Pl. 27, fig. 2, and _Elatomma scoparium_, but
differs from both in the double medullary shell.)
_Dimensions._--Diameter of the outer shell 0.15, middle 0.05, inner 0.025;
length of the spines 0.1.
_Habitat._--Central Pacific, Station 273, surface.
{260}2. _Pityomma piniferum_, n. sp.
Cortical shell thin walled, with irregular, roundish pores, connected with
both medullary shells by twenty stout radial beams, which are prolonged
outside into twenty large three-sided prismatic spines. These are longer
than the shell diameter and have three dentate edges, being branched like a
pine tree (with four to six ramified branches on each edge, decreasing in
size towards the distal end); similar to those of _Cladococcus abietinus_
(Pl. 27, fig. 3). Radial proportion of the three spheres = 1 : 2 : 8. Both
medullary shells with regular, circular pores, twice as broad as the bars.
_Dimensions._--Diameter of the outer shell 0.2, middle 0.05, inner 0.025;
length of the spines 0.25.
_Habitat._--South Pacific, Station 299 (Juan Fernandez), surface.
3. _Pityomma drymodes_, n. sp. (Pl. 29, fig. 9).
Cortical shell thin walled, connected with both medullary shells by very
numerous (one hundred to two hundred or more) very thin radial beams, which
are prolonged outside into thin branched radial spines, scarcely half as
long as the shell radius, each spine bearing six to nine simple branches.
Outer and middle shell uneven, with hill-shaped protuberances and valleys
between them; the connecting radial beams, which arise from the top of the
protuberances of the middle shell, are inserted into the deepest part of
the valleys of the outer shell. Radial proportion of the three spheres =
1 : 3 : 8. Outer medullary shell with small, irregular, roundish, or
polygonal pores, not much broader than the bars; innermost shell with
polygonal pores and very thin bars.
_Dimensions._--Diameter of the outer shell 0.28, middle 0.1, inner 0.033;
length of the spines 0.07, breadth 0.004.
_Habitat._--Central Pacific, Station 271, surface.
Subfamily CROMYOMMIDA,[140] Haeckel, 1881, Prodromus, pp. 449, 453.
_Definition._--#Astrosphærida# with four concentric spherical
lattice-shells.
Genus 104. _Cromyomma_,[141] Haeckel, 1881, Prodromus, p. 454.
_Definition._--#Astrosphærida# with four concentric lattice-spheres and
numerous simple radial spines of one kind.
The genus _Cromyomma_ is the common ancestral form of the Cromyommida, or
of those Astrosphærida in which the shell is composed of four concentric
spheres, connected by radial beams. Usually two of these are intracapsular
or medullary {261}shells, two extracapsular or cortical shells; the
distance between the former and the latter is greater than the distance
between either the two inner or the two outer shells. In some cases,
however (_e.g._, _Cromyomma zonaster_), the distance between all four
shells is equal.
Subgenus 1. _Cromyommetta_, Haeckel.
_Definition._--Pores of the outer cortical shell regular, of nearly equal
size and similar form.
1. _Cromyomma villosum_, n. sp. (Pl. 30, fig. 2).
Radial proportion of the four spheres = 1 : 2 : 4 : 5. Outer cortical shell
thick walled, densely covered with innumerable bristle-shaped radial
spines, half as long as the radius. Pores regular, circular, double-edged,
of the same breadth as the bars; ten to twelve on the radius. The thick
outer shell is so dark, that the outlines only of the other three shells
can be seen.
_Dimensions._--Diameter of the four shells--(A) outer cortical shell 0.2,
(B) inner cortical shell 0.16, (C) outer medullary shell 0.08, (D) inner
medullary shell 0.04; pores and bars of the outer shell 0.008; length of
the spines 0.04.
_Habitat._--Central Pacific, Station 267, depth 2700 fathoms.
2. _Cromyomma zonaster_, Haeckel.
_Acanthosphæra zonaster_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 285, Taf. ii. fig. 2.
Radial proportion of the four spheres = 2 : 3 : 4 : 5. Outer cortical shell
thick walled, densely covered with numerous bristle-shaped radial spines,
as long as the radius. Pores regular, circular, twice as broad as the bars;
eight to ten on the radius. The thick outer shell is so dark, that the
outlines only of the other three shells can be seen.
_Dimensions._--Diameter of the four shells--(A) 0.15, (B) 0.12, (C) 0.09,
(D) 0.06; pores of the outer shell 0.01, bars 0.005; length of the spines
0.08.
_Habitat._--Arctic Ocean, Greenland (depth 1000 fathoms), "Alert"
Expedition.
3. _Cromyomma perplexum_, Stöhr.
_Cromyomma perplexum_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 95, Taf.
iii. fig. 5.
Radial proportion of the four spheres = 1 : 2 : 3 : 4. Outer cortical shell
thick walled, densely covered with short conical spines, as long as the
diameter of the pores. These are regular, circular, three times as broad as
the bars; six to eight on the radius. The thick outer shell is so dark,
that the outlines only of the three other shells can be seen.
_Dimensions._--Diameter of the four shells--(A) 0.17, (B) 0.13, (C) 0.087,
(D) 0.043; pores of the outer shell 0.015, bars 0.005; length of the spines
0.02.
_Habitat._--Fossil in the Tertiary rocks of Sicily (Grotte) Stöhr.
{262}Subgenus 2. _Cromyommura_, Haeckel.
_Definition._--Pores of the outer cortical shell irregular, of different
size and form.
4. _Cromyomma perspicuum_, n. sp. (Pl. 30, fig. 8).
_Cromyosphæra perspicua_, Haeckel, 1879, Atlas (pl. xxx. fig. 8).
Radial proportion of the four shells = 1 : 2.5 : 6 : 9. Outer cortical
shell very thin walled, with thread-like bars, and irregular, polygonal
pores; inner cortical shell with similar pores, but with thicker bars. Both
medullary shells with regular, circular pores (the outer three times as
broad as the inner). Numerous thin radial beams connect the latter with the
former; other very thin and numerous beams connect the two cortical shells,
and are prolonged outside into short bristle-shaped spines (often longer
than in the figure).
_Dimensions._--Diameter of the four shells--(A) 0.18, (B) 0.12, (C) 0.05,
(D) 0.02; pores of the outer shell 0.01 to 0.02; length of the spines 0.01
to 0.03.
_Habitat._--Central Pacific, Station 274, surface.
5. _Cromyomma quadruplex_, Haeckel.
_Cromyomma quadruplex_, Haeckel, 1862, Monogr. d. Radiol., p. 446.
_Haliomma quadruplex_, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d.
Wiss. Berlin, p. 243.
Radial proportion of the four spheres = 1 : 3 : 7 : 10. Outer cortical
shell thin walled, irregularly covered with numerous angular spines, as
long as the radius. Pores of all four shells irregular, roundish,
increasing in size from the first to the fourth.
_Dimensions._--Diameter of the four shells--(A) 0.15, (B) 0.1, (C) 0.045,
(D) 0.015; pores of the outer shell 0.01 to 0.02; length of the spines
0.07.
_Habitat._--North Atlantic, Station 353, depth 2965 fathoms.
6. _Cromyomma macroporum_, Stöhr.
_Cromyomma macroporum_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 95, Taf.
iii. fig. 4.
Radial proportion of the four spheres = 1 : 3 : 6 : 9. Outer cortical shell
thick walled, densely covered with short conical spines, as long as the
diameter of the pores; the latter are irregular, roundish, or polygonal,
larger and smaller alternating.
_Dimensions._--Diameter of the four shells--(A) 0.1, (B) 0.066, (C) 0.033,
(D) 0.011; pores of the outer shell 0.033 to 0.016, bars 0.003; length of
the spines 0.01.
_Habitat._--Fossil in the Tertiary rocks of Sicily, Grotte, Stöhr.
7. _Cromyomma circumtextum_, n. sp. (Pl. 30, fig. 4).
Radial proportion of the four spheres = 1 : 2 : 5 : 7. Outer cortical
shell very delicate and thin walled, with thread-like bars and large,
irregular, polygonal meshes (larger than the innermost shell); {263}inner
cortical shell also with irregular, polygonal pores, three to nine times as
broad as the thick bars. Both medullary shells with subregular, circular
pores (the outer three times as broad as the inner). Radial spines twelve
to twenty, three-sided prismatic, stout, piercing the three outer shells,
inserted on the innermost; their outer part pyramidal, half as long as the
radius.
_Dimensions._--Diameter of the four shells--(A) 0.22, (B) 0.15, (C) 0.07,
(D) 0.03; meshes of the outer shell 0.02 to 0.04; length of the outer
spines 0.05.
_Habitat._--Central Pacific, Station 266, depth 2750 fathoms.
8. _Cromyomma mucronatum_, n. sp. (Pl. 30, figs. 5, 5_a_).
Radial proportion of the three spheres = 1 : 2 : 3 : 6. Outer cortical
shell thin walled, with large, irregular, roundish pores and crested
three-sided bars; inner cortical shell with regular, circular, hexagonally
formed pores (four times as broad as the bars). Both medullary shells with
simple, small, regular, circular pores (fig. 5_a_). Twelve radial spines
three-sided prismatic, dagger-shaped, with three teeth, as long as the
diameter of the innermost shell.
_Dimensions._--Diameter of the four shells--(A) 0.24, (B) 0.12, (C) 0.08,
(D) 0.04; meshes of the outer shell 0.02 to 0.04; length of the spines
0.04.
_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.
Genus 105. _Cromyechinus_,[142] Haeckel, 1881, Prodromus, p. 454.
_Definition._--#Astrosphærida# with four concentric lattice-spheres and
numerous simple spines of two different kinds; larger main spines and
smaller by-spines.
The genus _Cromyechinus_ differs from _Cromyomma_ in the same way as
_Echinomma_ from _Actinomma_; the radial spines being differentiated into
two different kinds; a larger number of small by-spines, and a smaller
number of large main spines.
1. _Cromyechinus icosacanthus_, n. sp. (Pl. 30, fig. 1).
Radial proportion of the three spheres = 1 : 2 : 6 : 8. Outer cortical
shell very delicate, with very small, regular, circular pores, covered with
very numerous bristle-shaped by-spines, half as long as the radius; inner
cortical shell with very large, irregular, polygonal pores, three to eight
times as broad as the bars. Both medullary shells with regular, circular
pores, connected with the former by twenty regularly disposed, very thin
bars; these are prolonged outside into twenty very stout, three-sided
prismatic main spines, as long as the radius, which arise from the inner
cortical shell, and at the distal end are cuspidate.
_Dimensions._--Diameter of the four shells--(A) 0.16, (B) 0.13, (C) 0.04,
(D) 0.02; pores of the outer cortical shell 0.003, of the inner 0.03, bars
0.003; length of the spines 0.08.
_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.
{264}2. _Cromyechinus dodecacanthus_, n. sp. (Pl. 30, figs. 3, 3_a_).
Radial proportion of the four spheres = 1 : 3 : 10 : 12. Outer cortical
shell very delicate, with very small, regular, circular pores, covered with
numerous short bristle-shaped by-spines, scarcely one-fourth as long as the
radius; inner cortical shell with very large, irregular, polygonal pores,
twice to six times as broad as the bars. Both medullary shells with very
small, regular, circular pores, connected with the former by twelve
regularly disposed, thin radial beams; these are prolonged outside into
twelve strong, three-sided pyramidal main spines, one-third as long as the
shell diameter. (Differs from the foregoing only in the number and form of
the radial spines.)
_Dimensions._--Diameter of the four shells--(A) 0.12, (B) 0.1, (C) 0.03,
(D) 0.01; pores of the outer cortical shell 0.002, of the inner 0.02, bars
0.002; length of the spines 0.04, basal breadth 0.01.
_Habitat._--South Atlantic, Station 325, surface.
3. _Cromyechinus polyacanthus_, n. sp.
Radial proportion of the four spheres = 1 : 2 : 8 : 10. Outer cortical
shell of the same structure as the inner, with irregular, roundish pores,
twice to six times as broad as the bars. Both medullary shells with small,
regular, circular pores, twice as broad as the bars. Connecting radial
beams forty to sixty, thin, cylindrical, prolonged outside into forty to
sixty strong conical main spines, about as long as the radius. Between
these, numerous thin bristle-shaped by-spines, nearly of the same length.
_Dimensions._--Diameter of the four shells--(A) 0.25, (B) 0.2, (C) 0.05,
(D) 0.025; pores of both cortical shells 0.01 to 0.03; length of the spines
0.12.
_Habitat._--North Pacific, Station 237, surface.
Genus 106. _Cromyodrymus_,[143] Haeckel, 1881, Prodromus, p. 454.
_Definition._--#Astrosphærida# with four concentric lattice-spheres and
numerous branched radial spines.
The genus _Cromyodrymus_ differs from its ancestral form, _Cromyomma_, in
the ramification of the radial spines, and exhibits therefore the same
relation to it that _Pityomma_ among the Actinommida bears to _Actinomma_.
1. _Cromyodrymus quadricuspis_, n. sp. (Pl. 30, figs. 7, 7_a_).
Radial proportion of the four shells = 1 : 3 : 6 : 12. All four shells with
regular, circular pores, about twice as broad as the bars. Radial
proportion of the pores in the four shells = 2 : 4 : 2 : 1. Radial spines
fifty to sixty, three-sided prismatic, half as long as the radius, with
three recurved teeth, each spine in this way bearing four points.
{265}_Dimensions._--Diameter of the four shells--(A) 0.16, (B) 0.08, (C)
0.04, (D) 0.013; length of the spines 0.03 to 0.04, breadth 0.007.
_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.
2. _Cromyodrymus abietinus_, n. sp. (Pl. 30, fig. 6).
Radial proportion of the four shells = 1 : 2 : 5 : 11. All four shells with
irregular, roundish pores, twice to four times as broad as the bars. Radial
proportion of the pores in the four shells = 9 : 3 : 2 : 1. Radial spines
eighty to one hundred and twenty, about as long as the radius, branched
like a pine tree, with six to twelve ramified branches.
_Dimensions._--Diameter of the four shells--(A) 0.22, (B) 0.1, (C) 0.04,
(D) 0.02; length of the spines 0.12, breadth 0.006.
_Habitat._--South-east Pacific (Juan Fernandez), Station 299, surface.
Subfamily CARYOMMIDA,[144] Haeckel.
_Arachnosphærida_, Haeckel, 1862, Monogr. d. Radiol., p. 354; Prodromus,
1881, p. 454.
_Definition._--#Astrosphærida# with five or more concentric spherical
lattice-shells.
Genus 107. _Caryomma_,[145] n. gen.
_Definition._--#Arachnosphærida# with five to six or more concentric
spherical lattice-shells; two inner (intracapsular) medullary and three or
more outer (extracapsular) cortical shells, composed of ordinary
lattice-work; distance between the former and the latter greater than
between any other two shells.
The genus _Caryomma_ may be regarded as a _Cromyomma_, in which the number
of the cortical shells is increased to three, four, or more. These lie
outside the central capsule, whilst two medullary shells lie within it, and
are connected with the former by numerous radial spines piercing the wall
of the capsule. The ordinary lattice-work is not arachnoidal, as in the
three following genera.
1. _Caryomma regulare_, n. sp.
Radial proportion of the five shells = 1 : 2 : 6 : 8 : 10. All five shells
with regular, circular pores, twice to three times as broad as the bars,
and gradually increasing in size from the innermost to the outermost shell.
Radial beams connecting them twenty, prolonged on the surface into twenty
stout, three-sided pyramidal, radial spines, half as long as the radius,
regularly disposed.
_Dimensions._--Diameter of the five shells--(A) 0.25, (B) 0.2, (C) 0.15,
(D) 0.05, (E) 0.025.
_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.
{266}2. _Caryomma irregulare_, n. sp.
Radial proportion of the six shells = 1 : 2.5 : 8 : 10.5 : 13 : 15. Both
inner (medullary) shells with regular, circular pores, the other four
(cortical) shells with irregular, roundish pores, gradually increasing in
size from the innermost to the outermost shell. Radial spines sixty to
eighty, pyramidal, irregularly disposed.
_Dimensions._--Diameter of the six shells--(A) 0.3, (B) 0.26, (C) 0.21, (D)
0.16, (E) 0.05, (F) 0.02.
_Habitat._--Central Pacific, Station 265, depth 2900 fathoms.
Genus 108. _Arachnopila_,[146] n. gen.
_Definition._--#Astrosphærida# with five to ten or more cortical,
concentric, polyhedral, or spherical lattice-shells, composed of a very
thin cobweb-like network; innermost shell with hexagonal (regular) or
polygonal (irregular) meshes; other shells with simple triangular meshes,
without diagonal threads between them.
The genus _Arachnopila_, together with the two following genera, forms the
peculiar small group of large Arachnosphærida, separated from the true
Caryommida by the totally different structure and disposition of the
numerous concentric shells; the former exhibits a similar relation to the
latter that the Diplosphærida bears to the Elatommida among the dispherical
Haliommida. The concentric shells (five to ten or more) lie outside the
central capsule, and are composed of very delicate, cobweb-like threads.
From the innermost shell arise numerous, three-sided prismatic, very long
spines, from which at equal regular distances arise lateral branches (three
pairs from each spine, and one pair from each corner). In _Arachnopila_
these threads pass directly from one spine to the other, and form simple,
large, triangular meshes between them. The concentric shells are not
connected by interwoven diagonal threads.
1. _Arachnopila hexagonella_, n. sp.
Innermost shell with regular hexagonal pores; its diameter twice as long as
the equal distance between every two concentric shells. Radial spines
twenty to forty, each with twenty to twenty-four verticils.
_Dimensions._--Diameter of the innermost shell 0.1; distance between the
concentric shells 0.05.
_Habitat._--Central Pacific, Station 271, surface.
2. _Arachnopila polygonella_, n. sp.
Innermost shell with irregular, polygonal pores; its diameter fully as long
as the equal distance between every two concentric shells. Radial spines
sixty to eighty, each with twelve to sixteen verticils.
_Dimensions._--Diameter of the innermost shell 0.04; distance between the
concentric shells 0.04.
_Habitat._--Central Pacific, Station 266, surface.
{267}Genus 109. _Arachnopegma_,[147] Haeckel, 1881, Prodromus, p. 454.
_Definition._--#Astrosphærida# with five to ten or more cortical,
concentric, polyhedral, or spherical lattice-shells, composed of a very
thin, cobweb-like network; innermost shell with hexagonal or polygonal
meshes; other shells with simple triangular meshes, connected to one
another by diagonal threads between them.
The genus _Arachnopegma_ differs from its ancestral form _Arachnopila_, in
the possession of peculiar diagonal threads, which connect the verticils or
nodal-points of every two neighbouring radial spines in two different
neighbouring concentric shells. In this case, therefore, not only do
triangular meshes lie in the spherical faces of the concentric spheres, but
also between them, in numerous oblique diagonal planes; a very rare and
remarkable structure, and forming a transition to spongy shells.
1. _Arachnopegma verticillatum_, n. sp.
Innermost shell with regular, hexagonal meshes; its diameter is the same as
the equal distance between each of the two shells. Threads of the network
smooth. Radial spines twenty to forty, each with fifteen to twenty
verticils.
_Dimensions._--Diameter of the innermost shell 0.04, distance between the
concentric shells 0.03 to 0.04.
_Habitat._--Central Pacific, Station 266, surface.
2. _Arachnopegma longispinum_, n. sp.
Innermost shell with regular, hexagonal meshes; its diameter half as large
as the equal distance between every two shells. Threads of the network
dentated or with small knots. Radial spines fifty to sixty, each with
twenty to twenty-five verticils.
_Dimensions._--Diameter of the innermost shell 0.02; distance between the
concentric shells 0.04 to 0.05.
_Habitat._--Central Pacific, Station 272, surface.
3. _Arachnopegma increscens_, n. sp.
Innermost shell with regular, hexagonal meshes; its diameter quite as large
as the distance between it and the second shell; only half as large as the
distance between the fourth and fifth shells. Forty to fifty radial spines,
each with fifteen to twenty verticils.
_Dimensions._--Diameter of the innermost shell (A) 0.025; distance between
the following shells--A, B = 0.025, B, C = 0.03, C, D = 0.04, D, E = 0.048,
E, F = 0.056, F, G = 0.064, &c.
_Habitat._--Central Pacific, Station 274, surface.
{268}Genus 110. _Arachnosphæra_,[148] Haeckel, 1862, Monogr. d. Radiol., p.
355.
_Definition._--#Astrosphærida# with five to ten or more cortical,
concentric, polyhedral, or spherical lattice-shells, composed of a very
thin cobweb-like network; innermost shell with hexagonal (regular) or
polygonal (irregular) meshes; other shells with larger, irregular,
polygonal meshes.
The genus _Arachnosphæra_ (accurately described by me in 1862, _loc. cit._)
differs from the two preceding genera in the irregular form of the large
meshes in all shells (except often the innermost). This is caused by the
ramification of the thin threads, which on each shell connect the
neighbouring spines. In _Arachnopila_ and _Arachnopegma_ the threads pass
directly and undivided from each spine to the neighbouring spine (three
pairs from the three edges), and therefore all meshes are triangular. In
_Arachnosphæra_ they become polygonal by irregular ramification of the
threads. There are here no diagonal threads.
Subgenus 1. _Arachnosphærella_, Haeckel.
_Definition._--Pores of the innermost shell regular, hexagonal.
1. _Arachnosphæra oligacantha_, Haeckel.
_Arachnosphæra oligacantha_, Haeckel, 1862, Monogr. d. Radiol., p. 356,
Taf. x. fig. 2, Taf. xi. fig. 3.
Innermost shell with regular, hexagonal meshes; its diameter three times as
long as the equal distances between every two concentric shells. Fifteen to
twenty radial spines scattered at wide intervals, each with six to eight
verticils.
_Dimensions._--Diameter of the innermost shell 0.12; distance between the
concentric shells 0.04 to 0.05.
_Habitat._--Mediterranean (Messina), surface, Haeckel.
2. _Arachnosphæra myriacantha_, Haeckel.
_Arachnosphæra myriacantha_, Haeckel, 1862, Monogr. d. Radiol., p. 357,
Taf. x. fig. 3, Taf. xi. fig. 4.
Innermost shell with regular, hexagonal meshes; its diameter twice as long
as the equal distances between every two concentric shells. At each
nodal-point occurs one radial spine with six to eight verticils (spines in
all one hundred to one hundred and twenty or more).
_Dimensions._--Diameter of the innermost shell 0.1; distance between the
concentric shells 0.04 to 0.05.
_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific,
surface.
{269}3. _Arachnosphæra dolichacantha_, n. sp.
Innermost shell with regular, hexagonal meshes, very small; its diameter
only as long as the equal distances between every two concentric shells. At
each nodal-point occurs one radial spine with twelve to sixteen verticils
(altogether thirty to forty spines).
_Dimensions._--Diameter of the innermost shell 0.05; distance between the
concentric shells 0.04 to 0.05.
_Habitat._--Central Pacific, Station 265 to 274, surface.
4. _Arachnosphæra increscens_, n. sp.
Innermost shell with regular, hexagonal meshes; its diameter three times as
long as the distance between it and the second shell, quite as long as the
distance between the fifth and sixth shells; the distances between the
concentric shells gradually increasing from the centre. Radial spines about
fifty to sixty, each with six to eight verticils.
_Dimensions._--Diameter of the innermost shell (A) 0.75; distances between
the following shells--A, B = 0.025, B, C = 0.037, C, D = 0.05, D, E =
0.062, E, F = 0.075, &c.
_Habitat._--Central Pacific, Station 271, surface.
Subgenus 2. _Arachnosphæromma_, Haeckel.
_Definition._--Pores of the innermost shell irregular, polygonal.
5. _Arachnosphæra tenuissima_, n. sp.
Innermost shell with irregular, polygonal meshes; its diameter twice as
long as the equal distance between every two concentric shells. Forty to
fifty radial spines, each with twelve to sixteen verticils.
_Dimensions._--Diameter of the innermost shell 0.1, distance between the
concentric shells 0.04 to 0.05.
_Habitat._--South Atlantic, Station 332, surface.
6. _Arachnosphæra velaris_, n. sp.
Innermost shell with irregular, polygonal meshes; its diameter twice as
long as the distance between it and the second shell, quite as long as the
distance between the third and fourth shells; the distance between the
concentric shells gradually increasing from the centre. Radial spines
twenty to thirty, each with ten to twelve verticils.
_Dimensions._--Diameter of the innermost shell (A) 0.5; distances of the
following shells--A, B = 0.025, B, C = 0.037, C, D = 0.05, D, E = 0.062, E,
F = 0.075.
_Habitat._--Tropical Atlantic, Station 347, surface.
{270}Subfamily SPONGIOMMIDA,[149] Haeckel.
_Definition._--#Astrosphærida# with spongy spherical or polyhedral shell
(with or without enclosed concentric lattice-shells).
Genus 111. _Spongiomma_,[150] n. gen.
_Definition._--#Astrosphærida# with solid spongy sphere, with numerous
simple radial spines, but without latticed medullary shells.
The genus _Spongiomma_ differs from its ancestral form, _Styptosphæra_, in
the development of simple radial spines on the surface of the solid sphere,
the entire mass of which is composed of an irregular, spongy wicker-work.
Subgenus 1. _Spongiommella_, Haeckel.
_Definition._--Radial spines on the surface of the spongy sphere all of the
same shape.
1. _Spongiomma radiatum_, n. sp.
Spongy framework of the solid sphere of the same structure throughout, with
small, irregular, polyhedral meshes and very thin thread-like bars. From
the surface arise very numerous (one hundred and twenty to one hundred and
sixty or more) straight, bristle-shaped radial spines, as long as the
radius of the sphere (counting from the middle part of it).
_Dimensions._--Diameter of the spongy sphere 0.2; length of the radial
spines 0.1.
_Habitat._--Central Pacific, Station 272, surface.
2. _Spongiomma denticulatum_, n. sp.
Spongy framework of the solid sphere of the same structure throughout, with
small, almost equal meshes, four to eight times as broad as the thin,
elegantly denticulated bars; from the surface arise very numerous (two
hundred to three hundred or more) curved, radial spines, as long as the
radius, and of the same form as the bars.
_Dimensions._--Diameter of the sphere 0.25; length of the spines 0.12.
_Habitat._--Central Pacific, Station 274, surface.
3. _Spongiomma spathillatum_, n. sp.
Spongy framework in the central part of the sphere much denser and darker,
and with smaller meshes than in the peripheral part in which are very thin
bars. Entire surface covered with {271}innumerable short, bristle-shaped
radial spines, only one-eighth as long as the radius, of the same elegant
form as in _Octodendron spathillatum_ (Pl. 18, figs. 2, 4); each spine
developed in a zig-zag fashion, with very small beards, with a delicate
spathillum (or coronal of beard spines) at the distal end.
_Dimensions._--Diameter of the spheres 0.16; length of the spines 0.01.
_Habitat._--South Pacific, Station 295, surface.
4. _Spongiomma clavatum_, n. sp.
Spongy framework in the central part of the sphere much denser and darker
than in the peripheral part. On the surface are sixty to eighty stout,
club-shaped radial spines, as long as the radius of the sphere, in the
proximal half three-sided prismatic, with three dentated edges; they begin
at the middle of the radius (where the denser inner framework changes into
the looser outer) and are very thin at first but increase slowly in
thickness towards the truncated distal end. (Similar to _Centrocubus
rhopalophorus_, Pl. 18, fig. 1, but without the cubical medullary shell.)
_Dimensions._--Diameter of the sphere 0.4; length of the spines 0.2.
_Habitat._--North Pacific, Station 241, surface.
Subgenus 2. _Spongiommura_, Haeckel.
_Definition._--Radial spines on the surface of the spongy sphere of two
different kinds; large main spines and small by-spines.
5. _Spongiomma helioides_, n. sp.
Spongy framework of the sphere everywhere of the same structure, with
almost equal meshes, ten to twelve times as broad as the bars. Sixteen to
twenty radial main spines, longer than the shell diameter, three-sided
prismatic, with three serrated edges, beginning about the middle of the
radius and increasing in thickness to the truncated distal end. Between
them occur numerous thin, bent, bristle-shaped by-spines. (Very similar to
_Spongosphæra helioides_, Monogr. d. Radiol., Taf. xii. figs. 11-13, but
without medullary shells.)
_Dimensions._--Diameter of the sphere 0.3; length of the main spines 0.4,
of the by-spines 0.01.
_Habitat._--Tropical Atlantic, Station 352, surface.
6. _Spongiomma multiaculeum_, Haeckel.
_Spongechinus multiaculeatus_, Dunikowski, 1882, Denkschr. d. k. Akad. d.
Wiss. Wien, Bd. xlv. p. 29, Taf. v. figs. 60-63.
Spongy framework of the sphere very compact, with small meshes, scarcely
broader than the bars; four to eight large main spines, three-sided
pyramidal, longer than the shell radius; numerous (thirty to forty) thin
by-spines, scarcely half as long.
{272}_Dimensions._--Diameter of the sphere 0.16; length of the main spines
0.11, of the by-spines 0.03.
_Habitat._--Fossil in the Alpine Jura, Schafberg near Salzburg
(Dunikowski).
7. _Spongiomma asteroides_, n. sp.
Spongy framework in the central part of the sphere much denser and darker
than in the peripheral part. Sixty to eighty cylindro-conical main spines,
as long as the radius, between them are numerous straight, bristle-shaped
by-spines half that length.
_Dimensions._--Diameter of the sphere 0.28; length of the main spines 0.16,
of the by-spines 0.08.
_Habitat._--South Atlantic, Station 325, surface.
Genus 112. _Spongodrymus_,[151] Haeckel, 1881, Prodromus, p. 456.
_Definition._--#Astrosphærida# with solid spongy sphere, without latticed
medullary shell, with numerous branched radial spines.
The genus _Spongodrymus_ differs from the preceding _Spongiomma_ in the
ramification of the numerous radial spines, covering the surface of the
solid spongy sphere.
1. _Spongodrymus elaphococcus_, n. sp. (Pl. 18, fig. 9).
Spongy framework of the solid sphere equal throughout, on the surface
arising in the form of very numerous (sixty to eighty or more) spongy cones
with rather rhomboidal meshes. Each cone is prolonged into a very thin,
irregularly curved radial spine, which is twice as long as the shell
diameter, simple in the proximal half, branched like a tree in the distal
half; each arborescent spine has from sixteen to thirty-two terminal
branches, which fall in one spherical face. The branches of neighbouring
spines are partly connected by anastomoses, so that they begin to form an
outer spherical shell (cortical shell) with a looser spongy framework.
_Dimensions._--Diameter of the whole spherical skeleton (sphere formed by
the distal ends of the dichotomous branches) 0.9, of the inner solid spongy
sphere 0.02.
_Habitat._--Tropical Atlantic, Station 349, surface.
2. _Spongodrymus abietinus_, n. sp.
Spongy framework denser and darker in the central part of the sphere than
in the peripheral part, with rather coarse meshes and thick bars. From the
surface arise very numerous (sixty to eighty) stout, radial branches, as
long as the shell radius, branched like a pine tree (with six to twelve
ramified branches). Similar in structure to _Cromyodrymus abietinus_ (Pl.
30, fig. 6), but with a quite irregular spongy texture in the central
sphere.
_Dimensions._--Diameter of the sphere 0.3; length of the spines 0.015.
_Habitat._--Central Pacific, Station 272, surface.
{273}Genus 113. _Spongechinus_,[152] Haeckel, 1881, Prodromus, p. 456.
_Definition._--#Astrosphærida# with hollow, spongy sphere, without latticed
medullary shell in the central cavity, and with numerous simple radial
spines.
The genus _Spongechinus_ differs from its ancestral form, _Plegmosphæra_,
in the development of numerous radial spines on the surface of the spongy
sphere, within which is enclosed a large spherical central cavity.
1. _Spongechinus setosus_, n. sp.
Spongy sphere three times as broad as its inner cavity, with a very
delicate, equal framework. Entire surface covered with short, straight,
bristle-shaped radial spines, about half as long as the radius.
_Dimensions._--Diameter of the sphere 0.2, of its inner cavity 0.07; length
of the spines 0.05.
_Habitat._--North Atlantic, Azores, surface.
2. _Spongechinus serrulatus_, n. sp.
Spongy sphere twice as broad as its inner cavity, with a delicate, equal
framework. Entire surface covered with short, curved, radial spines, which
are elegantly denticulated, and as long as the shell radius.
_Dimensions._--Diameter of the sphere 0.3, of its cavity 0.15; length of
the spines 0.15.
_Habitat._--Central Pacific, Station 274, surface.
3. _Spongechinus cavus_, n. sp.
Spongy sphere only one-fourth broader than the large inner cavity, its
spongy wall being only one-fourth as thick as the radius, composed of three
to four strata of irregular, small meshes. Surface covered with short,
bristle-shaped, curved spines, one-third as long as the radius.
_Dimensions._--Diameter of the sphere 0.5, of its inner cavity 0.4; length
of the spines 0.08.
_Habitat._--North Atlantic, Station 354, surface.
Genus 114. _Spongothamnus_,[153] n. gen.
_Definition._--#Astrosphærida# with hollow, spongy sphere, without latticed
medullary shell in the central cavity, and with numerous branched radial
spines.
The genus _Spongothamnus_ differs from the preceding _Spongechinus_ in the
ramification of the numerous radial spines, covering the surface of the
hollow spongy sphere; {274}it therefore exhibits the same relation to the
latter that _Spongodrymus_ bears to _Spongiomma._
1. _Spongothamnus furcatus_, n. sp.
Spongy sphere twice as broad as its inner cavity, with very delicate bars,
and irregular, dense framework. From the surface arise one hundred and
fifty to one hundred and eighty thin, forked, bristle-shaped spines, half
as long as the radius; both fork branches one-third as long as the basal or
simple part.
_Dimensions._--Diameter of the sphere 0.3, of its inner cavity 0.15; length
of the spines 0.08.
_Habitat._--North Pacific, Station 241, surface.
2. _Spongothamnus scoparius_, n. sp.
Spongy sphere four times as broad as its inner cavity, with thick bars and
rather loose framework. From the surface arise sixty to eighty broom-shaped
radial spines, as long as the radius, each in the basal half simple, in the
distal half with six to twelve irregularly ramified branches (similar to
the spines of _Cromyodrymus abietinus_, Pl. 30, fig. 6).
_Dimensions._--Diameter of the sphere 0.4, of the inner cavity 0.1; length
of the spines 0.2.
_Habitat._--Central Pacific, Station 271, surface.
Genus 115. _Spongopila_,[154] Haeckel, 1881, Prodromus, p. 456.
_Definition._--#Astrosphærida# with a single, spherical, latticed medullary
shell, immediately enveloped by the spongy framework of the cortical shell;
on the surface of the latter are numerous radial spines.
The genus _Spongopila_ is a _Spongoplegma_ with radial spines. On the other
hand it may be derived either from _Elaphococcus_, by communication of the
branched spines, or from _Arachnosphæra_, by development of spongy branches
between the concentric spheres.
1. _Spongopila dichotoma_, n. sp.
Medullary shell with regular, hexagonal meshes, six times as broad as the
bars. From each nodal-point (between every three meshes) arises a
bristle-shaped radial spine, which is dichotomously branched. By
communication of the neighbouring branches the loose spongy framework of
the spherical cortical shell is formed, which is four times as broad as the
medullary shell. On the surface occur very numerous bristle-shaped radial
spines, as long as the diameter of the medullary shell. (May be derived
from _Elaphococcus_.)
_Dimensions._--Diameter of the spongy cortical shell 0.3, of the medullary
shell 0.08.
_Habitat._--Tropical Atlantic, Station 347, surface.
{275}2. _Spongopila verticillata_, n. sp.
Medullary shell with regular, hexagonal meshes, four times as broad as the
bars. From its surface arise forty to sixty, three-sided prismatic radial
spines, bearing eight to ten verticils of lateral branches, each verticil
with six forked branches (two from each edge). By irregular ramification of
these branches, and communication in all directions, the loose spongy
framework of the cortical shell originates, which is six times as broad as
the medullary shell. The free distal ends of the spines are as long as the
shell radius. (May be derived from _Arachnosphæra_.)
_Dimensions._--Diameter of the spongy cortical shell 0.6, of the medullary
shell 0.1.
_Habitat._--Tropical Pacific, Station 200, surface.
Genus 116. _Rhizoplegma_,[155] Haeckel, 1881, Prodromus, p. 456.
_Definition._--#Astrosphærida# with a single, spherical, latticed medullary
shell, which is not armed with by-spines, but connected by stout radial
main spines with the spongy cortical shell.
The genus _Rhizoplegma_ is immediately allied to the foregoing
_Spongopila_, but differs from it in the large interval separating both
shells. In this interval lies the wall of the central capsule, which is
only pierced by the radial spines connecting both shells.
Subgenus 1. _Rhizoplegmarium_, Haeckel.
_Definition._--No free lateral branches of the radial spines between the
two shells.
1. _Rhizoplegma polyacanthum_, n. sp.
Spongy cortical shell with a very fine dense framework and nearly smooth
surface (without superficial by-spines). Its inner cavity is four times as
broad as the medullary shell, which exhibits regular, hexagonal meshes.
Radial spines sixty to eighty, three-sided prismatic, with three smooth
edges, without lateral branches between both shells; their free outer part
as long as the shell radius.
_Dimensions._--Diameter of the spongy cortical shell 0.3, of its inner
cavity 0.2, of the medullary shell 0.05.
_Habitat._--Central Pacific, Station 274, surface.
2. _Rhizoplegma spirale_, n. sp.
Spongy cortical shell with a very delicate loose framework and bristly
surface. Its inner cavity three times as broad as the medullary shell,
which exhibits regular, hexagonal meshes. {276}Radial spines thirty to
forty, prismatic, with three smooth, spirally contorted edges, without
lateral branches between the two shells; their free outer part half as long
as the shell radius.
_Dimensions._--Diameter of the spongy cortical shell 0.2, of its inner
cavity 0.12, of the medullary shell 0.04.
_Habitat._--Central Pacific, Station 265, surface.
3. _Rhizoplegma trigonacantha_, n. sp.
Spongy cortical shell with a rather loose framework and coarse bars, with
nearly smooth surface (without by-spines). Its inner cavity twice as broad
as the medullary shell, which exhibits irregular, roundish pores. Radial
spines forty to sixty, prismatic, with three smooth straight edges, without
free branches between the two shells; their outer pyramidal part only
one-third of the shell radius. (Very similar to the common _Rhizosphæra
trigonacantha_, but with simple medullary shell.)
_Dimensions._--Diameter of the spongy shell 0.2, of its inner cavity 0.16,
of the medullary shell 0.08.
_Habitat._--North Atlantic, Station 353, surface.
Subgenus 2. _Rhizoplegmidium_, Haeckel.
_Definition._--Between the two shells free lateral branches arise from the
three edges of the radial spines.
4. _Rhizoplegma radicatum_, n. sp. (Pl. 15, figs. 9, 9_a_).
Spongy cortical shell with a very loose framework; on the surface are
innumerable thin, forked, or repeatedly dichotomous by-spines. Its inner
cavity three times as broad as the medullary shell, which exhibits regular,
hexagonal meshes (fig. 9_a_). Radial spines twelve, prismatic, with
straight dentated edges, their outer pointed part as long as the shell
radius. Each spine between the two shells has a verticil of three forked
lateral branches (fig. 9_a_). The central capsule completely distends the
medullary shell, and forces out through each mesh a hernia-shaped process
(fig. 9).
_Dimensions._--Diameter of the spongy shell 0.5, of its inner cavity 0.25,
of the medullary shell 0.08.
_Habitat._--Central Pacific, Station 271, surface.
5. _Rhizoplegma lychnosphæra_, n. sp. (Pl. 11, fig. 5).
_Lychnosphæra rhizoplegma_, Haeckel, 1879, Atlas (pl. xi. fig. 5).
Spongy cortical shell with a very loose framework, composed of long thin
beams as in _Lychnosphæra regina_ (Pl. 11, figs. 1-4). Surface covered with
short bristles. Its inner cavity six times as broad as the medullary shell,
which exhibits regular, hexagonal meshes. Radial spines twelve, prismatic,
with three smooth edges; their outer pointed part half as long as the shell
radius. Each spine has three verticils of three forked branches; the first
verticil is free {277}between the two shells, while the two following
verticils, by communication of their ramules, form the irregular framework.
Central capsule with many herniæ, forced out through the meshes of the
medullary shell (fig. 5).
_Dimensions._--Diameter of the spongy shell 0.7, of its inner cavity 0.45,
of the medullary shell 0.07.
_Habitat._--South Pacific, Station 284, surface.
Genus 117. _Lychnosphæra_,[156] Haeckel, 1881, Prodromus, p. 453.
_Definition._--#Astrosphærida# with a single, spherical, latticed medullary
shell, which is armed with free radial by-spines, and connected by stout
radial main spines with the spongy cortical shell.
The genus _Lychnosphæra_, known only by one single, large, and very
remarkable species, mainly differs from the foregoing in the development of
free radial by-spines on the surface of the medullary shell, and in the
free interval between it and the cortical shell; but beyond this the loose
spongy framework of the latter exhibits a very remarkable structure,
figured in Pl. 11.
1. _Lychnosphæra regina_ (Pl. 11, figs. 1-4).
Medullary shell (fig. 3) with regular, circular, hexagonally framed pores,
twice as broad as the bars; from each hexagon-corner arises a radial,
bristle-shaped by-spine, as long as the diameter. Twelve radial main spines
each as broad as one of the meshes, three-sided prismatic, six to eight
times as long as the medullary shell. From their three leaf-shaped (often
somewhat denticulated or spirally contorted) edges arise four verticils of
lateral branches, each composed of three forked, thin branches. The forked
branches of the first verticil end free between the two shells (figs. 2,
3), while the two following verticils are ramified, and, by anastomosis of
their branches, compose the loose spongy framework of the cortical shell.
On the surface of the latter arise numerous radial (zig-zag-shaped)
by-spines. The fourth verticil is terminal, with three shorter, thicker,
dentated, simple branches, which constitute, together with the distal apex
of the spine itself, a bunch of four terminal spines. The large central
capsule completely distends the medullary shell, and forces out by its
pores numerous club-shaped herniæ (fig. 1).
_Dimensions._--Diameter of the spongy cortical shell 0.6, of its inner
cavity 0.4, of the central capsule 0.22, of the medullary shell 0.06;
length of the radial spines 0.4, breadth 0.01.
_Habitat._--Central Pacific, Station 271, surface.
Genus 118. _Centrocubus_,[157] n. gen.
_Definition._--#Astrosphærida# with a single, cubical medullary shell,
immediately surrounded by the spongy framework of the cortical shell; from
the eight corners {278}of the central cube arise eight primary radial
spines, and often others from the framework between them.
The genus _Centrocubus_ and the following closely allied _Octodendron_ may
represent a peculiar small group of Spongiommida, remarkable for the
regular, cubical form of the medullary shell, which is composed of twelve
thin rods, corresponding to the twelve edges of a mathematical cube; from
the eight corners invariably arise eight primary radial spines, the
branches of which form the spongy cortical shell.
1. _Centrocubus octostylus_, n. sp.
Radial spines eight, arising from the eight corners of the cubiform,
regular, medullary shell, gradually increasing in thickness towards the
club-shaped distal end, which is five to six times as broad as the central
end. From the three denticulate edges of each spine arise six to eight
lateral branches, which ramify irregularly and form by their anastomosis
the spongy framework which is of nearly similar structure throughout, and
with large loose meshes. The free distal part of each spine is half as long
as the enclosed part.
_Dimensions._--Diameter of the sphere 0.6, of the central cube 0.02; length
of the spines 0.15, distal thickness 0.02.
_Habitat._--Central Pacific, Station 271, surface.
2. _Centrocubus cladostylus_, n. sp. (Pl. 18, fig. 1).
Radial spines thirty-two, club-shaped, at the distal end eight to ten times
as broad as at the basal end. Eight primary spines arise from the eight
corners of the regular, cubiform medullary shell, and from these, in the
form of lateral branches, twenty-four secondary spines arise with concavely
curved bases (three from the three denticulate edges of each spine, at
nearly equal distances from the centre). The free distal end of each of the
thirty-two spines is of the same shape, about half as long as the radius of
the spongy sphere; framework much looser in the outer than in the inner
part.
_Dimensions._--Diameter of the sphere 0.8, of the central cube 0.02; length
of the spines 0.2, distal thickness 0.02.
_Habitat._--North Pacific, Station 256, surface.
3. _Centrocubus polystylus_, n. sp.
Radial spines sixty to eighty, club-shaped, four to six times as broad at
the distal as at the basal end. Eight primary spines arise from the eight
corners of the regular, cubiform medullary shell, the remainder either
springing as lateral branches from the three denticulate corners of the
former, or arising within the spongy framework, which is much denser and
darker in the central than in the peripheral part. The free distal end of
each spine is one-third as long as the radius.
{279}_Dimensions._--Diameter of the sphere 0.9, of the central cube 0.02;
length of the spines 0.15, distal thickness 0.02.
_Habitat._--South Pacific, Station 295, surface.
Genus 119. _Octodendron_,[158] n. gen.
_Definition._--#Astrosphærida# with a single, cubical medullary shell, and
eight primary radial spines arising from its eight corners; these are
connected at equal distances by a latticed, spherical, cortical shell, from
which the spongy framework directly springs; often from the latter
secondary radial spines arise.
The genus _Octodendron_ has the same regular, cubical medullary shell as
the preceding _Centrocubus_, but differs from it in the wide interval
separating the medullary shell from the inner spherical face of the spongy
cortical shell, the two being connected only by eight radial beams, arising
from the eight corners of the cube.
Subgenus 1. _Octodendridium_, Haeckel.
_Definition._--Only eight primary radial spines, arising from the eight
corners of the central cube.
1. _Octodendron cubocentron_, n. sp. (Pl. 18, fig. 3).
Radial spines eight, club-shaped, with three denticulate, straight edges,
twice as long as the diameter of the central cavity of the cubical spongy
shell; the inner face of the latter (or the "inner cortical shell")
exhibits the form of a large cube, the spongy sides of which are parallel
with the simple square sides of the central cube. The thin eight radial
beams, connecting the corresponding corners of both cubes, are not thicker
than the edge-bars of the central cube, whilst their outer prolongations
are much thicker, with four to six verticils of lateral branches. Surface
of the thin walled, loose, spongy shell armed with short simple thorns.
_Dimensions._--Diameter of the spongy shell 0.2, of its inner cavity 0.1,
of the central cube 0.02; length of the spines 0.2 (from the centre 0.3).
_Habitat._--Central Pacific, Station 266, surface.
2. _Octodendron spirale_, n. sp.
Radial spines eight, three-sided prismatic, three times as long as the
diameter of the inner shell-cavity; their three edges denticulated and
spirally contorted around the spine axis. Thickness of the loose spongy
shell-wall equal to the radius of the inner cavity, three times as large as
the central cube. Surface covered, with numerous thin, bristle-shaped, bent
spinules.
{280}_Dimensions._--Diameter of the spongy shell 0.24, of its inner cavity
0.12, of the central cube 0.02; length of the spines 0.4, breadth 0.01.
_Habitat._--North Pacific, Station 254, surface.
3. _Octodendron pinetum_, n. sp.
Radial spines eight, three-sided prismatic, three to four times as long as
the diameter of the inner shell-cavity, with three spirally contorted
edges. From each spine arise at equal distances (equal to the half radius
of the cavity) fifteen to twenty verticils of branches which increase in
size from the base of the spine. Each verticil is composed of six forked
branches (two from each spine-edge); the inferior are richly branched, and
form by their connection the loose network of the spongy cortical shell,
the surface of which is covered with numerous bent threads. Each spine
bears a resemblance to a pine tree.
_Dimensions._--Diameter of the spongy shell 0.3, of its inner cavity 0.15,
of the central cube 0.02; length of the spines 0.5 to 0.6, breadth 0.01.
_Habitat._--Central Pacific, Station 272, surface.
4. _Octodendron araucaria_, n. sp.
Radial spines eight, three-sided prismatic, with three spirally contorted
edges, eight to ten times as long as the diameter of the inner shell-cavity
(the free distal portion twice to three times as long). From each spine
arise at equal distances thirty to thirty-five verticils of branches, which
decrease in size towards the distal end. Each verticil is composed of six
forked branches (two from each spine-edge); the inferior are richly
ramified and form by their connection the loose spongy framework; the
distal branches bear on the free end elegant spathillæ (as in the following
species). Surface covered with innumerable straight bristles, as long as
the cavity radius, and ending with a spathilla. Diameter of the central
capsule about equal to the radius of the spongy sphere, its membrane is
double-edged.
_Dimensions._--Diameter of the spongy shell 1.4 mm., of its inner cavity
0.14, of the central cube 0.02, of the central capsule 0.5 to 0.6; length
of the spines 0.9 to 1.2, breadth 0.02.
_Habitat._--South Pacific, Station 288, surface.
5. _Octodendron spathillatum_, n. sp. (Pl. 18, figs. 2, 4).
Radial spines eight, three-sided prismatic, with contorted edges, five to
eight times as long as the diameter of the shell-cavity (the free part
twice as long). From each spine arise ten to twelve verticils of lateral
branches; each verticil composed of three forked branches. The proximal
larger branches ramify richly, and form by their connection the loose
spongy framework of the spherical shell; the distal smaller branches are
simple or bifurcated, and the ramules are provided with an elegant
spathillum at the end (fig. 4). Entire surface of the spongy sphere covered
with innumerable bristle-shaped radial spines (half as long as the cavity
radius), zig-zag, bent, with beards, and with a spathillum at the end.
{281}_Dimensions._--Diameter of the spongy sphere 1 mm., of its central
cavity 0.15, of the central cube 0.02; length of the spines 1 to 1.2 mm.,
breadth 0.008.
_Habitat._--Central Pacific, Station 271, surface.
Subgenus 2. _Octodendronium_, Haeckel.
_Definition._--Radial spines thirty-two or more, eight primary (arising
from the eight corners of the central cube) and twenty-four or more
secondary (between them).
6. _Octodendron verticillatum_, n. sp.
Radial spines thirty-two, with three denticulate straight edges, six to
eight times as long as the diameter of the shell-cavity; the distal parts
half free. Eight primary spines arise from the eight corners of the central
cube, twenty-four secondary from the edges of these (a verticil of every
three from each primary spine). Distal free parts of all thirty-two spines
equal. Each spine with eight to ten verticils of forked lateral branches,
without spathillæ. Surface of the spongy sphere covered with short simple
bristles.
_Dimensions._--Diameter of the spongy shell 0.3, of its cavity 0.12, of the
central cube 0.02; length of the spines 0.7 to 1 mm., breadth 0.02.
_Habitat._--South Pacific, Station 291, surface.
7. _Octodendron contortum_, n. sp.
Radial spines thirty-two, disposed in a similar manner to those of the
former species (eight primary and twenty-four secondary); also the spongy
shell of the same shape. The difference arises in the form of the spines,
the three edges of which are much broader and spirally contorted around the
axis; and thus the corresponding branches of the verticil do not lie in the
same meridian-plane, but alternate one with another.
_Dimensions._--Diameter of the spongy shell 0.4, of its cavity 0.1, of the
central cube 0.02; length of the spines 0.8 to 1.2, breadth 0.04.
_Habitat._--Central Pacific, Station 274, surface.
8. _Octodendron arboretum_, n. sp.
Radial spines sixty to ninety, three-sided prismatic, with spirally
contorted and denticulate edges, six to eight times as long as the diameter
of the inner shell-cavity. Eight primary arise from the eight corners of
the central cube, twenty-four others from their three edges (as in the two
former species); the remaining thirty to sixty spines seem to arise between
the former and immediately from the dense spongy framework, which is twice
as thick as the diameter of the inner shell-cavity. The numerous verticils
of the free distal part are of equal shape in all the spines, composed of
three forked branches in the terminal, and of more ramified branches in the
inferior parts. Entire surface of the spongy shell covered with simple
radial bristles, without spathillæ.
{282}_Dimensions._--Diameter of the spongy shell 0.75, of its central
cavity 0.15, of the central cube 0.02; length of the spines 0.9 to 1.2,
breadth 0.02.
_Habitat._--Tropical Pacific, Station 225, surface.
Genus 120. _Spongosphæra_,[159] Ehrenberg, 1847, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 54.
_Definition._--#Astrosphærida# with two concentric latticed medullary
shells, connected by radial beams; the outer is immediately enveloped by
the spongy framework, and bears numerous radial spines.
The genus _Spongosphæra_ (in the definition here restricted) differs from
_Spongopila_ in the double medullary shell, which in the latter is simple;
it exhibits to the latter the same relation that _Spongodictyon_ among the
Liosphærida bears to _Spongoplegma_. The outer medullary shell of
_Spongosphæra_ is immediately enveloped by the spongy wicker-work, which
everywhere pierces the wall of the central capsule.
1. _Spongosphæra streptacantha_, Haeckel.
_Spongosphæra streptacantha_, Haeckel, 1862, Monogr. d. Radiol., p. 455,
Taf. xxvi. figs. 1-3.
Spongy shell of polyhedric, irregular outline, the framework being
prolonged sheath-like into the eight to twelve radial spines, which are
quite irregularly distributed, very large, three-sided prismatic, with
three serrated, spirally contorted edges; their length is twice to four
times as great as the diameter of the spongy body; they arise with thinner
bases from the outer medullary shell, which is three times as broad as the
inner, both having roundish pores, twice to four times as broad as the
bars; surface without radial by-spines.
_Dimensions._--Diameter of the spongy shell 0.2 to 0.6, outer medullary
shell 0.04 to 0.06, inner 0.012 to 0.016.
_Habitat._--Cosmopolitan; common in all warmer seas, surface.
2. _Spongosphæra polyacantha_, J. Müller.
_Spongosphæra polyacantha_, J. Müller, 1858, Abhandl. d. k. Akad. d.
Wiss. Berlin, p. 32, Taf. iv. figs. 1-4.
Spongy shell spherical, with ten to twenty large radial spines, which arise
with thinner bases from the medullary shell, and are prominent on the
surface at different lengths; they are three-sided prismatic (not
four-sided), with three leaf-shaped straight edges. Whilst the spongy
framework is much looser than in the preceding species, both medullary
shells have nearly the same shape.
_Dimensions._--Diameter of the spongy shell 0.2 to 0.5, outer medullary
shell 0.04 to 0.06, inner 0.012 to 0.016.
_Habitat._--Mediterranean (Nice); Atlantic, Station 353, surface.
{283}Subgenus _Spongosphæromma_, Haeckel.
_Definition._--Radial spines on the surface of the spongy shell of two
different kinds; large piercing main spines and small superficial
by-spines.
3. _Spongosphæra helioides_, Haeckel.
_Spongosphæra helioides_, Haeckel, 1862, Monogr. d. Radiol., p.456, Taf.
xii. figs. 11-13.
Spongy shell spherical, with numerous curved, bristle-shaped by-spines on
the surface, as long as the radius. Main spines ten to twenty, irregularly
disposed, prismatic, with three dentated, spirally contorted edges, broader
toward the distal end. Outer medullary shell three times as broad as the
inner, with polygonal meshes (of the same size as those in the spongy
framework) and fine bars.
_Dimensions._--Diameter of the spongy shell 0.2, outer medullary shell
0.02, inner 0.007.
_Habitat._--Mediterranean (Messina).
4. _Spongosphæra quadricuspis_, n. sp.
Spongy shell spherical, with numerous curved, bristle-shaped by-spines on
the surface, half as long as the radius. Main spines twenty to thirty,
irregularly disposed, prismatic, with three dentated, spirally contorted
edges, and at the distal end four strong pyramidal divergent teeth (three
as terminations of the edges, the fourth as end of the spine axis). Outer
medullary shell twice as broad as the inner, both having circular, regular
pores, twice to three times as broad as the bars.
_Dimensions._--Diameter of the spongy shell 0.3, outer medullary shell
0.04, inner 0.013.
_Habitat._--Central Pacific, Station 272, surface.
Genus 121. _Rhizosphæra_,[160] Haeckel, 1860, Monatsber. d. k. preuss.
Akad. d. Wiss. Berlin, p. 840.
_Definition._--#Astrosphærida# with two concentric latticed medullary
shells, connected by radial beams; from the outer arise numerous radial
spines, which at equal distances are connected by a latticed spherical
cortical shell, surrounded by a spongy framework.
The genus _Rhizosphæra_ exhibits the same relation to _Spongosphæra_ that
_Rhizoplegma_ bears to _Spongopila_; but in the latter the latticed
medullary shell is simple, in the two former double. The wall of the
central capsule is pierced only by the radial spines connecting the
medullary and the cortical shells.
1. _Rhizosphæra trigonacantha_, Haeckel.
_Rhizosphæra trigonacantha_, Haeckel, 1862, Monogr. d. Radiol., p. 452,
Taf. xxv. figs. 1-7.
Central cavity of the spongy cortical shell twice as broad as the diameter
of the outer medullary shell. Bars of all three shells of the same breadth
as the thirty to fifty (or more) radial spines, {284}which are three-sided
prismatic; their outer free distal end only as long as the diameter of the
inner medullary shell.
_Dimensions._--Diameter of the spongy shell 0.25, of its inner cavity 0.2,
outer medullary shell 0.1, inner 0.05.
_Habitat._--Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, surface
from many Stations.
2. _Rhizosphæra serrata_, n. sp. (Pl. 18, figs. 5-7).
Central cavity of the spongy shell five times as broad as the diameter of
the outer medullary shell. Bars of all three shells of the same breadth as
the forty to sixty (or more) thin radial beams between them. These are
three-sided prismatic, with denticulate edges, scarcely half as broad as
their outer prolongations, which are half as long as the shell radius, and
possess three spirally contorted serrated edges. (The figured specimen is a
young one; in the older specimens the spongy framework of the cortical
shell is much more developed.)
_Dimensions._--Diameter of the spongy shell 0.3, of its central cavity
0.22, outer medullary shell 0.06, inner 0.02.
_Habitat._--Central Pacific, Stations 270 to 274, surface.
3. _Rhizosphæra leptomita_, Haeckel.
_Rhizosphæra leptomita_, Haeckel, 1862, Monogr. d. Radiol., p. 453, Taf.
xxv. figs. 8-10.
Central cavity of the spongy cortical shell twice as broad as the diameter
of the outer medullary shell; bars of both very thin, only one-third as
broad as the bars of the inner medullary shell. Radial spines thirty to
fifty (or more), curved, three-sided prismatic; inside the spongy shell as
thin as their bars, outside three times as broad.
_Dimensions._--Diameter of the spongy shell 0.27, of its inner cavity 0.2,
outer medullary shell 0.1, inner 0.05.
_Habitat._--Mediterranean (Messina); Atlantic, Stations 348 to 354,
surface.
----
Suborder PRUNOIDEA, Haeckel, 1883 (Pls. 13-17, 39, 40).
_Definition._--SPUMELLARIA with an ellipsoidal or cylindrical central
capsule, prolonged into one axis (sometimes articulate by annular
transverse strictures); with an ellipsoidal or cylindrical, fenestrated
siliceous shell (often articulate by annular strictures), invariably
prolonged into one axis. Fundamental form monaxon, usually with the poles
of the prolonged dimensive main axis equal.
The suborder #Prunoidea# comprises those SPUMELLARIA in which the
fenestrated spherical shell appears prolonged into one axis. The geometric
fundamental form of the shell, which in the #Sphæroidea# was a sphere, in
this case therefore becomes an ellipsoid, and whilst in the former all axes
originally have the same value (Homaxonia), {285}here one main axis is
constantly larger than all other axes (Monaxonia). Usually both poles of
this main axis are equal (Haplopola); but in some genera both poles become
different (Diplopola).
In the #Sphæroidea# all planes going through the centre of the shell are
circular, whereas in the #Prunoidea# only those planes are circular which
are perpendicular to the main axis; all other planes going through the
centre are elliptical; the largest of these are the meridian planes, in
which is situated the main axis. Commonly all meridian planes are equal, as
no transverse axes (or cross axes) are differentiated.
In my Monograph (1862) only very few forms of #Prunoidea#, such as
_Didymocyrtis_ and _Spongurus_, are described, and the greater part of them
are distributed under different genera of #Sphæroidea#, such as _Haliomma_
and _Actinomma_. In my Prodromus (1881) I separated them as the family
Zygartida (p. 462). But it seems now much more convenient to restrict this
term to a particular family and to give a wider extension to the whole
suborder under the name #Prunoidea# (called after the characteristic
ellipsoidal form of a plum, or _Prunus_, with its stone).
The suborder #Prunoidea# comprises seven different families, of which the
Ellipsida constitutes the simplest and the probable common ancestral group.
In all Ellipsida the fenestrated shell is simple, and never composed of
concentric or twin shells. In their primitive genus _Cenellipsis_, the
whole shell is geometrically nothing more than a simple ellipsoid (Pl. 39,
figs. 1, 2). By development of radial spines it passes into _Ellipsidium_,
by development of spongy framework into _Spongellipsis_. In the greater
part of this family large spines are developed on both poles of the main
axis of the shell, but sometimes instead of these solid spines, two
opposite hollow fenestrated tubes are developed (_Pipettella_, Pl. 39, fig.
6).
The second family of #Prunoidea#, the Druppulida, is much richer in
different forms than the simple Ellipsida. In this case the ellipsoidal
shell is composed of two or three (rarely more) concentric shells.
Constantly one or two of these fenestrated shells are enclosed in the
central capsule, and may therefore be called "medullary shells"; and one or
two (rarely more) lie outside the central capsule, "cortical shells." The
inner medullary shells (one or two) are either spherical or ellipsoidal;
the outer cortical shells (one or two, rarely more) are always ellipsoidal.
All concentric shells are connected by radial beams. In the simplest form
of the subfamily, _Druppula_ (Pl. 39, fig. 3), one medullary shell is
connected with one cortical shell. By duplication of the medullary shell
arises _Prunulum_ (Pl. 39, fig. 4), and by duplication or multiplication of
the cortical shell _Cromyodruppa_ (Pl. 15, figs. 1-4) is formed. In by far
the greater portion of this subfamily large spines are developed on both
poles of the main axis of the cortical shell (Pls. 16, 17), but sometimes
also instead of these solid spines two opposite hollow fenestrated tubes
are developed (_Pipetta_, Pl. 39, figs. 7, 8).
{286}A third family of #Prunoidea#, closely allied to the two preceding
families, is the Spongurida, in which we include all #Prunoidea# with an
ellipsoidal or cylindrical, unjointed shell, in which the lattice-work of
the cortical shell is transformed into an irregular, siliceous framework.
In the simplest form, _Spongellipsis_, the simple lattice-shell of
_Cenellipsis_ is substituted by an external spongy envelope. In other cases
(_Spongurus_ and allied genera) the whole cavity of this external spongy
shell is distended with a fine spongy framework. The subfamily of
Spongodruppida is distinguished by the possession of a simple or double
latticed medullary shell; this lies in the midst of the central capsule,
and is connected by radial beams (perforating its membrane) with the
enveloping spongy cortical shell. The surface of the latter may bear either
radial spines, or two opposite strong polar spines, at the poles of the
main axis (Pl. 17, fig. 12).
Closely allied to the Ellipsida and Druppulida are two other families of
the #Prunoidea#, the Artiscida and Cyphinida, which differ from the former
by a circular constriction in the equatorial plane of the ellipsoidal
shell; and in this way assume a characteristic twin form, like a figure of
eight. In the Artiscida the shell is simple (as in the Ellipsida), whereas
in the Cyphinida it is composed of two or more concentric shells (as in the
Druppulida). The simplest form of the Artiscida is _Artiscus_ (Pl. 39, fig.
9), differing from _Cenellipsis_ in the ring-shaped, equatorial
constriction. In other Artiscida polar appendages are developed on both
poles of the main axis, either in the form of solid, strong spines
(_Stylartus_), or hollow fenestrated tubes (_Cannartus_, Pl. 39, fig. 10).
The family Cyphinida differs from the Druppulida in the equatorial
constriction of the shell, and from the Artiscida in the presence of two or
more concentric shells. One or two of these concentric fenestrated shells
are enclosed in the central capsule (and therefore may be called "medullary
shells"); the others (one or two, rarely more) lie outside of the central
capsule (therefore "cortical shells"). The internal "medullary shells" are
always spherical or somewhat lenticular, compressed from both sides; the
external "cortical shells" have constantly a ring-like constriction in the
equatorial plane, and "twin-shells" are therefore like a figure of eight.
The simplest form of this subfamily is _Cyphanta_, composed of a simple
medullary shell and a simple cortical shell, the two being connected in the
equatorial plane by radial beams. In Cyphonium (Pl. 39, fig. 12) the
medullary shell is doubled, and in _Cypassis_ (Pl. 39, fig. 13) the
cortical shell likewise. On both poles of the main axis strong spines are
often developed (_Cyphinus_, Pl. 39, fig. 14), or hollow fenestrated tubes
(_Cannartidium_, Pl. 39, figs. 16-19).
The equatorial constriction of the ellipsoidal shell, which characterises
the Artiscida and Cyphinida, is repeated or multiplied in the two following
families, in the Panartida and Zygartida; in the former we find three
ring-like strictures, in the latter five or more (lying in parallel
transverse planes); therefore the fenestrated shell is composed in the one
instance of four chambers, in the other of six or {287}more; all the
chambers form a single series and have a common main axis. All
constrictions lie in planes parallel to the equatorial plane of the
original ellipsoid; in the centre of the latter constantly lies a double
"medullary shell," composed of two concentric, either spherical or
lenticular, compressed shells. In all Panartida we call the two inner
chambers (on both sides of the equatorial constriction) "proximal
chambers," the two outer chambers (on the poles of the main axis) "distal
chambers." The four-chambered cortical shell of the Panartida is either
simple (in _Panartus_, Pl. 40, figs. 1-4) or double, with an external
mantle (as in _Peripanartus_, Pl. 40, figs. 5-7). The simplest form of the
subfamily is _Panartus_ (_loc. cit._). In this case also on both poles of
the main axis may be developed solid spines, or hollow fenestrated tubes
(_Panarium_, Pl. 40, fig. 9).
The seventh and last family of the #Prunoidea#, the Zygartida is most
nearly allied to the Panartida, and appears as a further developmental step
from that family. Whilst in the Panartida the cortical shell is constantly
four-chambered, with three parallel ring-like constrictions, in the
Zygartida it is always prolonged and composed of six or more chambers,
separated by five or more ring-shaped constrictions, in the middle of which
is the equatorial stricture. In the centre of the latter (as also in the
Panartida) always lies the double medullary shell, composed of two
concentric, spherical, or lenticular shells. The number of the chambers of
the cortical shells is commonly six or eight (with five to seven ring
strictures), but it often mounts to ten and sometimes to twenty (with
nineteen strictures), as in some species of _Zygartus_ (Pl. 40, fig. 13).
All the chambers lie in one series, one behind another, with a common main
axis. The cortical shell is usually simple (in _Ommatocampe_, Pl. 40, fig.
10), sometimes double (in _Desmocampe_, Pl. 40, fig. 12), rarely triple (in
ZYGOCAMPE, Pl. 40, fig. 13). In all three cases hollow fenestrated tubes
may be developed on the poles of the main axis.
The morphological references and the phylogenetic affinities of all
#Prunoidea# are so complex, that they seem to represent a quite natural
group; all forms of it may be derived from the common ancestral form
_Cenellipsis_. But a far more difficult question is the manner in which its
pedigree may be constructed. The oldest family is probably the simplest,
namely, Ellipsida. From this the Druppulida may be derived by production of
medullary shells, the Artiscida by equatorial constriction. The Cyphinida
can be produced either from the Druppulida by equatorial constriction or
from the Artiscida by development of medullary shells. The Panartida appear
as further developmental steps of the Cyphinida, by duplication of the
chamber number; and the Zygartida as further productions of the Panartida,
by increasing the number of the chambers.
The seven subfamilies of the #Prunoidea# can be arranged in two sections
according to the presence or absence of medullary shells. The Ellipsida,
Spongellipsida, and Artiscida possess a simple cortical shell, without a
medullary shell; they represent the {288}section Cenoprunida. All other
families possess medullary shells, and so represent the section
Coccoprunida.
Another character, which can be employed in the arrangement of the seven
subfamilies in some larger groups, is the presence or absence of ring-like
constrictions, by which the cortical shell is divided into chambers. I. The
Monoprunida comprise all forms without any constriction, of which the
Ellipsida are without a medullary shell, the Druppulida with one or two
medullary shells, and the Spongurida with a spongy cortical shell. II. The
Dyoprunida contain all forms with a cortical twin shell, or with two
chambers separated by one equatorial constriction, of which the Artiscida
are without a medullary shell and the Cyphinida have one or two medullary
shells. III. The Polyprunida comprise all forms with several (three or
more) constrictions, which separate four or more chambers, of which the
Panartida have three constrictions and four chambers, and the Zygartida
five or more constrictions and six or more chambers.
_The Central Capsule_ of the #Prunoidea# is originally ellipsoidal
(monaxial), and preserves this form in the greater part of the genera. In
some groups, where the axis of the ellipsoid is much prolonged, it passes
over to the cylindrical form (with hemispherical vaultings on both poles),
as in _Spongurus_ and _Spongocore_, in many Panartida and Zygartida. Very
often the ellipsoidal or cylindrical capsule gets annular transverse
constrictions, corresponding to those of the enveloping cortical shell (one
single, equatorial stricture in the Artiscida and Cyphinida, three
strictures in the Panartida, five or more in the Zygartida). In the
Cenoprunida (Ellipsida and Artiscida, also in _Spongellipsis_) the central
capsule lies freely in the cavity of the cortical shell, separated from its
inner surface by the jelly-envelope; in all other groups it contains a part
of the skeleton, the medullary shell and the beams which connect it with
the enveloping cortical shell.
_Synopsis of the Families of_ #Prunoidea#.
{a. Shell simple, latticed (not
{ spongy), without enclosed internal
{ enclosed internal shells, 1. ELLIPSIDA.
A. MONOPRUNIDA. {
{b. Shell composed of two or more
Shell without { concentric latticed shells
transverse stricture { (not spongy), 2. DRUPPULIDA.
{
{c. Shell partially or wholly
{ composed of an irregular spongy
{ framework, 3. SPONGURIDA.
B. DYOPRUNIDA. {
{d. Shell simple, without enclosed
Shell bilocular, { internal shells, 4. ARTISCIDA.
divided by an {
equatorial stricture {
into two communicating{e. Shell composed of two or more
hemi-ellipsoidal { concentric shells, 5. CYPHINIDA.
shells. {
C. POLYPRUNIDA. {f. Shell with three parallel
{ strictures and therefore four
Shell multilocular, { cameræ, 6. PANARTIDA.
divided by three {
or more parallel {g. Shell with five or more parallel
transverse strictures { strictures and therefore six
into four or more { or more cameræ, 7. ZYGARTIDA.
serial cameræ. {
{289}Family XI. #ELLIPSIDA#, Haeckel, 1882 (Pls. 13, 14, 39).
_Definition._--#Prunoidea# with simple ellipsoidal shell, without
equatorial stricture (without enclosed medullary shell); network a simple
lattice lamella, not spongy. Central capsule ellipsoidal or cylindrical,
without annular equatorial constriction.
The family #Ellipsida# comprises the simplest forms of #Prunoidea#, and
probably represents the ancestral forms of this whole suborder. The
fenestrated shell, which encloses the ellipsoidal central capsule, is a
perfectly simple "cortical shell" of the same form, without enclosed
"medullary shell." Its form is commonly a regular monaxial ellipsoid;
sometimes a little modified by unequal growth of the two poles of the main
axis. Two opposite large spines are often developed at these poles, or it
may be that instead of these, two hollow fenestrated tubes are present.
The ellipsoidal fenestrated shell exhibits in the regular Ellipsida all the
characters of a geometric ellipsoid; one main axis surpasses in length all
other possible axes. All sections going through this main axis are
"meridian sections," with elliptical periphery; all sections perpendicular
to the main axis are "transverse sections," with circular periphery. The
largest of these is the equatorial section, which divides the main axis
into halves. The diameter of this equatorial plane is the "minor axis" of
the ellipsoid.
The proportion of the two axes of the ellipsoidal shell, of the major
vertical or main axis and the minor horizontal or equatorial axis, is
commonly between 6 : 5 and 3 : 2. In the former case it approaches the
spherical shell, from which it is derived; in the latter case it becomes
almost fusiform or cylindrical. The network of silex, constituting the
shell, is constantly a simple latticed lamella, never composed of
concentric shells (as in Druppulida) or spongy (as in Spongurida). The
network is often very regular and elegant, in other cases irregular.
The simplest genus among the Ellipsida, and probably the common ancestral
form of the whole subfamily, is the genus _Cenellipsis_, possessing a
simple ellipsoidal shell without any appendages. It is derived from
_Cenosphæra_ (the simplest spherical shell) by the prolongation of one
axis. _Cenellipsis_ passes over into _Ellipsidium_ by the production of
radial spines on the surface (corresponding to _Heliosphæra_). _Axellipsis_
is a peculiar genus differing from _Cenellipsis_ in an axial rod, which
corresponds to the minor or equatorial axis. In all other genera of the
subfamily both poles of the main axis are distinguished by peculiar polar
prolongations, either hollow fenestrated tubes (as in _Pipettella_) or
strong solid spines. Both polar spines are of equal size and similar form
in _Ellipsoxiphus_, unequal in _Ellipsostylus_. From the latter is derived
_Lithapium_, by reduction and loss of one spine (so that only one remains);
_Lithomespilus_, by production of a bunch of several spines at one pole. In
the three latter genera both poles of the main axis are unequal, in all
others equal.
{290}The central capsule of the Ellipsida is in all cases ellipsoidal, and
occupies the largest part of the shell, being separated from its inner
surface by a thinner or thicker jelly-mantle.
_Synopsis of the Genera of Ellipsida._
-------------------------------------------------------------------------
Ellipsoidal shell without polar appendages (neither solid spines nor
hollow tubes at the poles of the axis).
-------------------------------------------------------------------------
Surface without {Shell cavity
radial spines. { simple, without
{ an axial rod, 122. _Cenellipsis_.
{
{Shell cavity
{ with a transverse
{ axial rod, 123. _Axellipsis_.
Surface covered with radial spines, 124. _Ellipsidium_.
-------------------------------------------------------------------------
Ellipsoidal shell with polar appendages (either solid spines or hollow
fenestrated tubes) at the poles of the main axis.
-------------------------------------------------------------------------
Solid spines of {Shell cavity
similar shape, { simple, without
at both poles of { axial rods, 125. _Ellipsoxiphus_.
the main axis. {
{Shell cavity
{ with a cross of
{ axial rods, 126. _Axoprunum_.
Solid spines of {Two polar spines
different shape, { of different
at both poles { shape, 127. _Ellipsostylus_.
of the main {
axis. {A bunch of spines
{ at one pole
{ only, 128. _Lithomespilus_
{
{Only a single
{ spine at one
{ one pole, 129. _Lithapium_.
Two hollow fenestrated tubes opposite,
at the poles of the main axis, 130. _Pipettella_.
Genus 122. _Cenellipsis_,[161] n. gen.
_Definition_.--#Ellipsida# with simple ellipsoidal shell, without radial
spines and without polar tubes.
The genus _Cenellipsis_ is the simplest and most primitive form, not only
among the Ellipsida, but also among the #Prunoidea#, and it may therefore
be regarded as the common ancestral form of the whole family. It
corresponds to _Cenosphæra_ among the #Sphæroidea#, to _Cenodiscus_ among
the #Discoidea#, to _Cenolarcus_ among the #Larcoidea#. Probably it is
derived from _Cenosphæra_ by prolongation of one axis.
Subgenus 1. _Cenellipsium_, Haeckel.
_Definition._--Network of the shell regular, with meshes of equal size and
similar form.
{291}1. _Cenellipsis primitiva_, n. sp.
Proportion of the longer axis of the ellipsoid to the shorter = 3 : 2.
Network of the thin wall very delicate and regular, with hexagonal pores.
All pores of nearly the same size and form, ten to twelve times as broad as
the bars; nine to twelve on the half equator of the shell. Surface smooth.
_Dimensions._--Longer axis of the ellipsoid 0.09 to 0.11, shorter axis 0.06
to 0.08; pores 0.01, bars between them 0.001.
_Habitat._--Pacific, central area, Station 272, surface.
2. _Cenellipsis faceta_, n. sp. (Pl. 39, fig. 1).
Proportion of the longer axis of the ellipsoid to the shorter = 4 : 3.
Network of the thin wall delicate and regular. All the pores of the same
size and form, circular, with a hexagonal frame, twice to three times as
broad as the bars; eight to ten on the half equator. Surface smooth or
slightly spiny.
_Dimensions._--Longer axis of the ellipsoid 0.12 to 0.13, shorter axis 0.09
to 0.1; pores 0.013, bars 0.005.
_Habitat._--Pacific, central area. Station 274, surface.
3. _Cenellipsis ehrenbergii_, Haeckel.
_Haliomma (?) cenosphæra_, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 74, Taf xxvi. fig. 5.
Proportion of the longer axis to the shorter = 2 : 1. Network of the thin
wall regular or subregular. All pores circular, nearly of the same size,
without hexagonal frame, three to four times as broad as the bars; eight to
nine on the half equator. Surface covered with small thorns.
_Dimensions._--Longer axis of the ellipsoid 0.16 to 0.2, shorter axis 0.08
to 0.1; pores 0.1, bars 0.003.
_Habitat._--Fossil in the Tertiary rocks of Barbados (Ehrenberg, Haeckel).
4. _Cenellipsis circopora_, n. sp.
Proportion of the longer axis to the shorter = 5 : 3. Network of the thin
wall delicate and regular. All pores circular, nearly of the same size,
without hexagonal frame, twice as broad as the bars; fifteen to twenty on
the half equator. Surface quite smooth.
_Dimensions._--Longer axis of the ellipsoid 0.15 to 0.2, shorter axis 0.09
to 0.12; pores 0.08, bars 0.4.
_Habitat._--North Pacific, Station 236, surface.
5. _Cenellipsis micropora_, n. sp.
Proportion of the longer axis to the shorter = 5 : 4. Network of the thick
wall quite regular. All pores circular, without hexagonal frame, very
small, scarcely half as broad as the bars; six to eight on the half
equator. Surface quite smooth.
{292}_Dimensions._--Longer axis of the ellipsoid 0.1, shorter axis 0.08;
pores 0.004, bars 0.01.
_Habitat._--South Pacific, Station 289, surface.
Subgenus 2. _Cenellipsula_, Haeckel.
_Definition._--Network of the shell irregular, with meshes of different
size or form.
6. _Cenellipsis heteropora_, n. sp.
Proportion of the longer axis to the shorter = 3 : 2 or = 5 : 3. Network of
the thin wall very irregular, with polygonal meshes of different size and
form (for the most part pentagonal or hexagonal, but also many tetragonal
or heptagonal). The largest pores four to six times as broad as the
smallest; ten to twenty pores on the half equator; bars between them thin.
Surface smooth or somewhat spiny.
_Dimensions._--Longer axis of the ellipsoid 0.18 to 0.22, shorter axis 0.1
to 0.12; pores 0.004 to 0.008, bars 0.001.
_Habitat._--Indian Ocean, near the Cocos Islands, surface, Rabbe.
7. _Cenellipsis maxima_, n. sp.
Proportion of the longer axis to the shorter = 3 : 2. Network of the thin
wall very irregular, with polygonal meshes of very different size and form,
twice to eight times as broad as the bars; fifty to sixty on the half
equator. Surface smooth.
_Dimensions._--Longer axis of the ellipsoid 0.36, shorter axis 0.25; pores
0.004 to 0.015, bars 0.002.
_Habitat._--Equatorial Atlantic, Station 347, surface.
8. _Cenellipsis ovulum_, n. sp.
Proportion of the longer axis to the shorter = 3 : 2. Network of the thin
wall very irregular, with roundish or longish pores of very different size
and form. Pores flat, with even margins, thirty to forty on the half
equator, twice to six times as broad as the bars. Surface smooth. (This
species being observed alive, showed a transparent central capsule of
ellipsoidal form, two-thirds as large as the shell.)
_Dimensions._--Longer axis of the ellipsoid 0.3, shorter axis 0.2; pores
0.04 to 0.012, bars 0.002.
_Habitat._--Indian Ocean, Ceylon, Haeckel; Pacific, central area, Station
266, surface.
9. _Cenellipsis infundibulum_, n. sp. (Pl. 39, fig. 2).
Proportion of the longer axis to the shorter = 3 : 2. Network of the thick
wall irregular, with roundish pores of different size and form. Pores
funnel-like, with prominent, irregular, spiny {293}crests between them,
their outer aperture three to four times as broad as the inner; twelve to
fifteen pores on the half equator. Surface prickly.
_Dimensions._--Longer axis of the ellipsoid 0.14, shorter axis 0.11; outer
aperture of the pores 0.01 to 0.012, inner aperture 0.003 to 0.004.
_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.
10. _Cenellipsis oblonga_, n. sp.
Proportion of the longer axis to the shorter = 2 : 1. Network of the thick
wall irregular, with roundish pores of different size and form. Pores with
prominent conical edges, about as broad as the bars; twenty to twenty-five
on the half equator. Sometimes each pore is prolonged into a short conical
tubulus.
_Dimensions._--Longer axis of the ellipsoid 0.22, shorter axis 0.12; pores
and bars 0.008 to 0.012.
_Habitat._--Pacific, central area, Station 265, depth 2900 fathoms.
Genus 123. _Axellipsis_,[162] n. gen.
_Definition._--#Ellipsida# with simple ellipsoidal shell, without radial
spines or polar tubes, but with an inner transverse axial rod, which
corresponds to the shorter axis of the ellipsoid.
The genus _Axellipsis_ differs from the simple _Cenellipsis_ in a very
peculiar character, namely, the presence of an inner siliceous bar marking
the minor axis of the ellipsoidal shell. If in some forms of _Druppula_
(e.g., Pl. 39, fig. 3) we remove the central medullary shell and prolong
both beams (connecting it with the cortical shell) till they unite in the
centre, we shall arrive at _Axellipsis_. Therefore _Axellipsis_ may be
derived in the same way from _Druppula_ as _Axoprunum_ is from
_Lithatractus_, by phyletic loss of the medullary shell.
1. _Axellipsis perforata_, n. sp.
Proportion of the major axis of the ellipsoid to the minor = 3 : 2. Pores
of the shell regular, circular, twice as broad as the bars; ten to twelve
on the half equator. Surface smooth.
_Dimensions._--Longer axis of the shell 0.12, shorter axis 0.08; pores
0.006, bars 0.003.
_Habitat._--Central area of the Pacific, Station 266, depth 2750 fathoms.
2. _Axellipsis lobata_, n. sp.
Proportion of the major axis to the minor = 5 : 4. Meshes of the shell
irregular, roundish, lobed, with three to six indentations (each mesh
formed by the confluence of three to six, commonly {294}four or five,
smaller pores); eight to nine meshes on the half equator, these being twice
to four times as broad as the bars.
_Dimensions._--Longer axis of the shell 0.1, shorter axis 0.08; pores 0.007
to 0.01, bars 0.003.
_Habitat._--Tropical zone of the Western Pacific, Station 225, surface.
Genus 124. _Ellipsidium_,[163] n. gen.
_Definition._--#Ellipsida# with simple ellipsoidal shell, with numerous
radial spines on the surface, without polar spines or tubes.
The genus _Ellipsidium_ differs from _Cenellipsis_ solely in the
development of numerous radial spines on the surface, and exhibits the same
phylogenetic relation to it that _Heliosphæra_ bears to _Cenosphæra_.
1. _Ellipsidium pandanidium_, n. sp.
Proportion of the longer axis of the ellipsoid to the shorter = 5 : 4.
Shell thick walled, with regular and hexagonal meshes, twice as broad as
the bars; eighteen to twenty on the half equator. In each hexagon-corner
(between three pores) arises a short, three-sided pyramidal spine, half as
long as the equatorial radius, and as thick at the base as a single mesh.
_Dimensions._--Major axis of the ellipsoid 0.15, minor 0.12; pores 0.006,
bars 0.003; length of the radial spines 0.03, basal breadth 0.006.
_Habitat._--Fossil in the Tertiary rocks of Barbados (Haeckel).
2. _Ellipsidium datura_, n. sp.
Proportion of the longer axis of the ellipsoid to the shorter = 4 : 3.
Shell thick walled, with regular, circular meshes, twice as broad as the
thick bars between them eight to ten meshes on the half equator. Outer
surface of the shell thorny, covered with short, conical, radial spines,
which are regularly distributed (one spine between every three meshes), and
about as long as the diameter of the meshes. (The shell is similar to the
outer shell of _Haliomma castanea_, Haeckel, Monogr. d. Radiol., Taf. xxiv.
fig. 4.)
_Dimensions._--Major axis of the ellipsoid 0.12, minor axis 0.09; meshes
0.012, bars 0.006.
_Habitat._--Western part of the Tropical Pacific, Station 225, depth 4475
fathoms.
3. _Ellipsidium artocarpus_, n. sp.
Proportion of the longer axis to the shorter = 3 : 2. Shell thick walled,
with regular, circular meshes, separated by deep furrows, which represent a
regular, hexagonal framework; on the half equator twelve to fifteen meshes,
scarcely broader than the broad bars between them. Outer {295}surface
spiny; between every three meshes arises a strong radial spine, twice to
three times as long as the diameter of the meshes; the base of the spine is
like a three-sided pyramid.
_Dimensions._--Major axis of the ellipsoid 0.12, minor axis 0.08; meshes
0.006, bars 0.005.
_Habitat._--Central area of the Pacific, Station 268, depth 2900 fathoms.
4. _Ellipsidium opuntia_, n. sp.
Proportion of the longer axis to the shorter = 5 : 4. Shell thin walled,
with irregular, roundish meshes of different size and form, about twice to
three times as broad as the irregular, thin bars between them; ten to
fifteen meshes on the half equator. Between the meshes arise numerous thin,
bristle-like, radial spines, about as long as the shorter radius of the
shell. The number of the meshes may be three to four times as great as the
number of the spines.
_Dimensions._--Major axis of the ellipsoid 0.15, minor axis 0.12; pores
0.006 to 0.01, bars 0.003 to 0.004.
_Habitat._--Southern Pacific, Station 284, surface.
5. _Ellipsidium echinidium_, n. sp.
Proportion of the longer axis to the shorter = 4 : 3. Shell thick walled,
with irregular, roundish pores of different size and form, about as large
or somewhat smaller than the broad bars; twelve to sixteen pores on the
half equator. On the surface, irregularly scattered, twenty to thirty
strong, three-sided pyramidal, radial spines, one-fourth to one-half as
long as the main axis.
_Dimensions._--Major axis of the ellipsoid 0.16, minor 0.12; pores and bars
0.002 to 0.008; length of the radial spines 0.04 to 0.08, basal breadth
0.01.
_Habitat._--Equatorial Atlantic, Station 347, depth 2250 fathoms.
Genus 125. _Ellipsoxiphus_,[164] Dunikowski, 1882, Denkschr. d. k. Akad. d.
Wiss. Wien, vol. xlv. p. 25.
_Definition._--#Ellipsida# with simple ellipsoidal shell, the main axis of
which is prolonged at both poles into two strong opposite spines of equal
size and similar form.
The genus _Ellipsoxiphus_ was established by Dunikowski (in 1882, _loc.
cit._) for those simple amphistylous fenestrated shells, formerly united
with _Xiphosphæra_, in which the mathematical form of the shell itself is
not a true sphere, but an ellipsoid. It may therefore be derived from
_Xiphosphæra_ by prolongation of the axis in which lie both polar spines;
but it may also be derived from _Cenellipsis_ by the production of two
equal spines at the poles of the main axis.
{296}Subgenus 1. _Ellipsoxiphetta_, Haeckel.
_Definition._--Network of the shell regular, with pores of equal size and
similar form.
1. _Ellipsoxiphus elegans_, n. sp. (Pl. 14, fig. 7).
Proportion of the major axis of the ellipsoid to the minor = 5 : 4. Shell
thick walled, with regular, circular meshes, separated by a regular,
hexagonal elevated framework. From each hexagon-corner arises (between
every three meshes) a short thin spine, about as long as the diameter of a
mesh; twelve to fourteen meshes on the half equator, of the same breadth as
the bars. Polar spines three-sided prismatic, cuspidate, about as long as
the axis of the shell. (This elegant and not uncommon species is remarkable
for its variations. By unequal development of both spines it passes over to
_Ellipsostylus_.) In the figured variety (Pl. 14, fig. 7) the ends of the
surface spines are connected by a very delicate network, so as to form an
outer veil. This may further be separated as a peculiar genus
_Ellipsoxiphium palliatum_.
_Dimensions._--Longer axis 0.08 to 0.13, shorter axis 0.06 to 0.11; pores
and bars 0.008; length of the polar spines 0.06 to 0.12, basal breadth
0.01.
_Habitat._--Pacific, central area, Stations 270 to 274, from 2350 to 2925
fathoms.
2. _Ellipsoxiphus flosculus_, n. sp.
Proportion of the major axis to the minor = 6 : 5. Shell very thick walled,
with regular, hexagonal meshes, eight to nine on the half equator, three to
four times as broad as the bars. The inner contour of the meshes is
circular, the outer six-lobed (similar to _Xiphostylus phasianus_, Pl. 13,
fig. 9). Polar spines three-sided pyramidal, about as long as the major
axis of the shell; their basal thickness equals one mesh.
_Dimensions._--Longer axis 0.12, shorter axis 0.1; pores 0.012 to 0.015,
bars 0.004; length of the polar spines 0.12 to 0.15, basal breadth 0.015.
_Habitat._--Fossil in the Tertiary rocks of Barbados (Teuscher).
3. _Ellipsoxiphus fragilis_, n. sp.
Proportion of the major axis to the minor = 4 : 3. Shell thin walled, with
regular, circular meshes, twice as broad as the bars; ten to twelve on the
half equator. Surface smooth. Polar spines cylindrical, at the apex
conical, half as long as the major axis.
_Dimensions._--Longer axis 0.16, shorter axis 0.12; pores 0.008, bars
0.004; length of the polar spines 0.09, basal breadth 0.008.
_Habitat._--South Atlantic, Station 325, surface.
Subgenus 2. _Ellipsoxiphilla_, Haeckel.
_Definition._--Network of the shell irregular, with pores of different size
or form.
{297}4. _Ellipsoxiphus claviger_, n. sp. (Pl. 14, fig. 3).
_Xiphosphæra clavigera_, Haeckel, 1881, Prodromus et Atlas.
Proportion of the major axis to the minor = 5 : 4. Shell thick walled, with
irregular network; meshes roundish or circular, double contoured, of
unequal size, twice to four times as broad as the bars; eight to ten on the
half equator. Polar spines club-shaped, with prominent edges, about as long
as the minor axis; thicker in their middle part than at both ends (differs
from _Xiphosphæra clavigera_ by the ellipsoidal form of the shell, and the
double length of the spines).
_Dimensions._--Longer axis 0.15. shorter axis 0.12; pores 0.007 to 0.015,
bars 0.004; length of the polar spines 0.12, thickness in the middle part
0.02.
_Habitat._--Central area of the Pacific, Station 272, depth 2600 fathoms.
5. _Ellipsoxiphus suessi_, Dunikowski.
_Ellipsoxiphus suessi_, Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss.
Wien, Bd. xlv. p. 26, Taf. v. fig. 50.
Proportion of the major axis to the minor = 7 : 5. Shell thick walled, with
irregular, roundish meshes, six to eight on the half equator, twice to
three times as broad as the bars. Polar spines nearly cylindrical, blunt,
as long as the major axis.
_Dimensions._--Longer axis 0.14; shorter axis 0.1; pores 0.018 to 0.023,
bars 0.01; length of the polar spines 0.12; thickness of them 0.035.
_Habitat._--Fossil in the Alpine Lias, Schafberg near Salzburg, Dunikowski.
6. _Ellipsoxiphus parvoforaminus_, Dunikowski.
_Ellipsoxiphus parvoforaminus_, Dunikowski, 1882, Denkschr. d. k. Akad.
d. Wiss. Wien, Bd. xlv. p. 26, Taf. v. fig. 51.
Proportion of the major axis to the minor = 7 : 6. Shell thick walled,
with irregular, roundish or oval meshes, ten to twelve on the half equator,
scarcely as broad as the bars. Polar spines conical, shorter than the
minor axis.
_Dimensions._--Longer axis 0.14, shorter axis 0.12; pores 0.016 to 0.01,
bars 0.01 to 0.02; length of the polar spines 0.1, basal thickness 0.045.
_Habitat._--Fossil in the Alpine Lias, Schafberg near Salzburg, Dunikowski.
7. _Ellipsoxiphus bipolaris_, n. sp. (Pl. 14, fig. 11).
_Xiphosphæra bipolaris_, 1881, Prodromus et Atlas.
Proportion of the major axis to the minor = 8 : 7. Shell thick walled,
with irregular, roundish meshes, twice to three times as broad as the bars;
sixteen to twenty on the half equator. Polar spines short and thick,
three-sided pyramidal, scarcely half as long as the shorter radius of the
shell; surrounding the base of every spine is a circle of eight to nine
shorter spines.
_Dimensions._--Longer axis 0.08, shorter axis 0.07; pores 0.003 to 0.007,
bars 0.002; length of the polar spines 0.02 to 0.03, basal thickness 0.02.
_Habitat._--Tropical part of the Western Pacific, Station 225, depth 4475
fathoms.
{298}8. _Ellipsoxiphus atractus_, n. sp. (Pl. 14, fig. 1).
Proportion of the major axis to the minor = 3 : 2. Shell spindle-shaped,
very thick walled, with roundish, very irregular meshes, twice to five
times as broad as the bars; eight to twelve on the half equator. The meshes
are partly simple, oblong, partly lobed or composed of two to four
(commonly three) confluent meshes. Surface smooth. Polar spines very short
and thick, shorter than the minor radius of the shell, three-sided
pyramidal, with prominent, somewhat contorted edges.
_Dimensions._--Longer axis 0.15, shorter axis 0.1; meshes 0.007 to 0.02,
bars 0.004; length of the polar spines 0.04, basal thickness 0.03.
_Habitat._--Central area of the Pacific, Station 268, depth 2900 fathoms.
Genus 126. _Axoprunum_,[165] n. gen.
_Definition._--#Ellipsida# with simple ellipsoidal shell, the main axis of
which is prolonged at both poles into two opposite spines of equal size and
similar form. Within the cavity of the shell four radial rods arise from
its inner surface, two in the main axis, two in the smallest axis,
perpendicular to the former; their free inner ends are at the same distance
from the centre.
The genus _Axoprunum_ possesses precisely the same shell as the foregoing
_Ellipsoxiphus_, but differs from it in a very remarkable peculiarity. The
two polar spines are centripetally prolonged into two internal beams, and
perpendicular to these are two other, opposite, transverse beams, marking
the minor axis of the ellipsoid. The free inner ends of all four radial
rods bear little thickened knobs, and are at the same distance from the
centre. It therefore appears as though a central, spherical, medullary
shell had been lost, and this gives a strong support to the important
hypothesis, that in many #Sphærellaria#, where the medullary shell is
absent, it may have been lost by phylogenetic reduction or retrograde
metamorphosis. In this case _Axoprunum_ (and _Ellipsoxiphus_) would arise
from _Lithatractus_.
1. _Axoprunum stauraxonium_, n. sp. (Pl. 48, fig. 4).
Shell ellipsoidal, one and one-third times as long as broad, with smooth
surface. Network regular, with circular meshes four times as broad as the
bars. Two polar spines three-sided pyramidal, half as long as the shell, as
thick at the base as a single mesh. Four inner radial beams (lying, two in
the major and two in the minor axis of the ellipsoid) very thin, at the
central free ends knob-like, thickened. The distance between two opposite
beams equals one-third of the minor axis, and indicates probably the
diameter of the lost spherical medullary shell. (Three perfect and complete
specimens of the same size and shape were observed.)
{299}_Dimensions._--Major axis of the ellipsoid 0.14, minor axis 0.11;
pores 0.012, bars 0.003; length of the polar spines 0.07, basal breadth
0.012. (Diameter of the lost medullary shell 0.03?)
_Habitat._--South Atlantic, Station 338, depth 1990 fathoms.
Genus 127. _Ellipsostylus_,[166] n. gen.
_Definition._--#Ellipsida# with simple ellipsoidal shell, the main axis of
which is prolonged at both poles into two opposite spines of different size
or form.
The genus _Ellipsostylus_ differs from _Ellipsoxiphus_ only in the unequal
size or different form of the polar spines, which in the former are equal.
This difference does not seem important at first, but in the further
development it produces very singular and strange forms. Theoretically it
is always important, because the fundamental haplopolar form of the monaxon
body becomes diplopolar by this differentiation.
Subgenus 1. _Ellipsostyletta_, Haeckel.
_Definition._--Network of the shell regular, with pores of equal size and
similar form.
1. _Ellipsostylus ornithoides_, n. sp.
Proportion of the major axis of the ellipsoid to the minor = 4 : 3. Shell
thin walled, with regular, circular meshes and hexagonal framework between
them, like that of _Xiphostylus favosus_ (Pl. 13, fig. 4). Circular pores
about as broad as the bars; eight to nine on the half equator. Surface
smooth. Polar spines three-sided pyramidal, as broad at the base as a
single hexagon; the longer spine as long as the major axis, the shorter
half as long.
_Dimensions._--Longer axis of the ellipsoidal shell 0.16, shorter axis
0.12; pores and bars 0.006; length of the longer polar spine 0.16, of the
shorter 0.08.
_Habitat._--North Pacific, Station 241, depth 2300 fathoms.
2. _Ellipsostylus avicularis_, n. sp.
Proportion of the major axis to the minor = 3 : 2. Shell thick walled, with
regular, rosette-shaped meshes, three times as broad as the bars; ten to
twelve on the half equator. Every mesh on the outer margin with five to six
rounded lobes, as in _Xiphostylus phasianus_ (Pl. 13, fig. 9). Surface
smooth. Polar spines sharp edged, thick; the longer straight and equal to
the longer axis, the shorter half as long, shaped like a bird's head.
_Dimensions._--Longer axis 0.18, shorter axis 0.12; pores 0.015, bars
0.005.
_Habitat._--South Pacific, Station 300, depth 1375 fathoms.
{300}3. _Ellipsostylus psittacus_, n. sp. (Pl. 13, fig. 6).
Proportion of the major axis to the minor = 4 : 3. Shell thin walled, with
regular or subregular rosette-shaped meshes, twice as broad as the bars;
eight to nine on the half equator; each mesh with three to four rounded
lobes. Surface smooth. Polar spines sharp edged, very unequal; longer spine
about twice as long as the major axis, somewhat curved; shorter spine
scarcely longer than the radius, shaped like a bird's head.
_Dimensions._--Longer axis 0.08, shorter axis 0.06; pores 0.01, bars 0.005;
length of the polar spines--longer 0.15, shorter 0.05.
_Habitat._--Central area of the Pacific, Station 266, depth 2750 fathoms.
4. _Ellipsostylus aquila_, n. sp. (Pl. 13, fig. 1).
Proportion of the major axis to the minor = 7 : 6. Shell thick walled, with
subregular, circular meshes, five to six times as broad as the bars; ten to
twelve on the half equator. Surface smooth. Polar spines sharp edged
(six-sided?), very unequal; longer spine straight, about equal to the minor
axis; shorter spine obliquely inserted, scarcely half as long, shaped like
a bird's head.
_Dimensions._--Longer axis 0.15, shorter axis 0.13; pores 0.02, bars 0.004;
length of the polar spines--longer 0.1, shorter 0.05.
_Habitat._--Central area of the Pacific, Station 272, depth 2600 fathoms.
5. _Ellipsostylus columba_, n. sp. (Pl. 13, fig. 3).
Proportion of the major axis to the minor = 4 : 3. Shell egg-shaped, thin
walled, with regular, circular meshes, three times as broad as the bars;
ten to twelve on the half equator. Surface somewhat thorny. Polar spines
nearly of equal length (equal to the major axis), but of very different
form; one straight, pyramidal, and obliquely inserted, the other like a
bird's head.
_Dimensions._--Longer axis 0.08, shorter 0.06; pores 0.003, bars 0.01;
length of the spines 0.09.
_Habitat._--South Atlantic, Station 332, surface.
6. _Ellipsostylus ciconia_, n. sp. (Pl. 13, fig. 8).
Proportion of the major axis to the minor = 7 : 5. Shell egg-shaped, thick
walled; the meshes very small, regular, circular, three times as broad as
the bars; sixteen to twenty on the half equator. Surface uneven. Polar
spines nearly cylindrical, pointed; the smaller obliquely inserted, equal
to the major axis; the larger more than twice as long and thick, furrowed
at its base. (Compare with this and the allied species _Rhabdolithis pipa_,
Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. i. fig. 27.)
_Dimensions._--Longer axis 0.07, shorter 0.05; pores 0.003, bars 0.001;
length of the polar spines--longer 0.2, shorter 0.08.
_Habitat._--North Pacific, Station 253, depth 3125 fathoms.
{301}Subgenus 2. _Ellipsostylissa_, Haeckel.
_Definition._--Network of the shell irregular, with pores of different size
or form.
7. _Ellipsostylus megadictya_, Haeckel.
_Stylosphæra megadictya_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 299, Taf. viii. fig. 13.
Proportion of the major axis to the minor = 5 : 4. Shell thin walled, with
irregular, roundish, large meshes, four to five times as broad as the bars;
only four to five on the half equator. Surface smooth. Polar spines
straight, thin, angular; the shorter equal to the minor axis, the longer
four times as large.
_Dimensions._--Longer axis 0.05, shorter axis 0.04; meshes 0.01, bars
0.002; length of the polar spines--longer 0.12, shorter 0.03.
_Habitat._--Philippine Sea, 3300 fathoms, Ehrenberg.
8. _Ellipsostylus gallinula_, n. sp.
Proportion of the major axis to the minor = 3 : 2. Shell thick walled, with
irregular, roundish meshes, twice to four times as broad as the bars; eight
to ten on the half equator. Surface thorny. Polar spines conical, straight;
the longer twice as long as the major axis, the minor scarcely half as
long.
_Dimensions._--Longer axis 0.15, shorter 0.12; pores 0.01 to 0.02, bars
0.002 to 0.004.
_Habitat._--North Pacific, Station 253, surface.
9. _Ellipsostylus hirundo_, n. sp. (Pl. 13, fig. 2).
Proportion of the major axis to the minor = 4 : 3. Shell thick walled, with
irregular, roundish meshes, three to five times as broad as the bars; eight
to ten on the half equator. The inner aperture of every mesh is fenestrated
by a delicate lamella of silex, perforated by six to eight very small
circular pores. Polar spines sharp edged, more or less curved, the shorter
equal to the minor axis, the longer twice as long.
_Dimensions._--Longer axis 0.16, shorter 0.12; pores 0.01 to 0.02, bars
0.003 to 0.006; length of the polar spines--longer 0.24, shorter 0.12.
_Habitat._--Pacific, central area, Station 268, depth 2900 fathoms; the
same form also fossil in the rocks of Barbados.
Genus 128. _Lithomespilus_,[167] Haeckel, 1881, Prodromus, p. 450.
_Definition._--#Ellipsida# with simple ellipsoidal or oviform shell, the
main axis of which bears at one pole a single spine, at the other a bunch
of several spines.
{302}The genus _Lithomespilus_ differs from the closely allied
_Ellipsoxiphus_ in the further differentiation of both poles of the main
axis. One pole exhibits only a single polar spine, the other pole a group
of several spines, peculiarly grouped together. It differs from the similar
_Sphæromespilus_ (Pl. 14, figs. 12, 13) in the ellipsoidal form of the
shell.
1. _Lithomespilus phloginus_, n. sp. (Pl. 14, fig. 16).
Proportion of the major axis of the ellipsoid to the minor = 4 : 3. Shell
thick walled, with circular pores of different size, the breadth of which
equals that of the bars; twelve to fifteen pores on the half equator.
Surface smooth, with the exception of a circumpolar region covered with
numerous thick spines of unequal size, which surround the large single
polar spine and are curved like a bow against its axis. This larger polar
spine is straight, and equals in length the major axis of the shell. The
other and opposite polar spine is scarcely one-fourth as long, perfectly
simple, very stout, and of a three-sided pyramidal shape.
_Dimensions._--Longer axis of the ellipsoidal shell 0.08, shorter axis
0.06; pores 0.002 to 0.006, bars 0.003 to 0.005; length of the polar
spines--longer 0.08, shorter 0.02.
_Habitat._--Indian Ocean, near Madagascar, depth 1200 fathoms, Smith.
2. _Lithomespilus phlogoides_, n. sp. (Pl. 14, fig. 17).
Proportion of the major axis to the minor = 5 : 4. Shell very thick walled,
with roundish, double-contoured pores of different size and form, twice to
three times as broad as the bars; sixteen to eighteen pores on the half
equator. Surface smooth, with the exception of a circumpolar region covered
with numerous thin spines of unequal size, which surround the large single
polar spine and are curved like a bow against its axis. This larger polar
spine is straight, and equals half the size of the major axis of the shell;
the other polar spine (sometimes double, as in the figured specimen) is
much shorter, being scarcely one-fourth as long.
_Dimensions._--Longer axis of the shell 0.08, shorter axis 0.065; pores
0.003 to 0.006, bars 0.002 to 0.004; length of the polar spines--longer
0.04, shorter 0.01.
_Habitat._--Central area of the Pacific, Stations 270 to 272, depth 2425 to
2925 fathoms.
3. _Lithomespilus flammeus_, n. sp.
_Stylosphæra species_, Bury, 1862, Polycystins of Barbados, pl. xi. fig.
3.
Proportion of the major axis to the minor = 4 : 3. Shell thick walled, with
irregular, roundish pores, about as broad as the bars; ten to twelve pores
on the half equator. Surface spiny. Length of the conical straight spines
increasing towards the poles; each polar spine surrounded by a circumpolar
group of larger, somewhat curved spines. The larger polar spine equals in
length the major axis; the smaller is scarcely half as long. (The figure,
given by Bury, is not quite exact; there the spines are situated in the
pores, instead of between them. In my specimen the polar spines were not
branched.)
{303}_Dimensions._--Longer axis of the shell 0.12, shorter axis 0.09; pores
and bars 0.004 to 0.006; length of the polar spines--longer 0.12, shorter
0.06.
_Habitat._--Fossil in Barbados.
4. _Lithomespilus flammabundus_, n. sp. (Pl. 14, fig. 14).
Proportion of the major axis to the minor = 4 : 3. Shell thin walled, with
irregular, roundish pores, partly simple, partly composed of three to six
confluent pores; only six to eight pores on the half equator, twice to four
times as broad as the bars. Surface spiny. Length of the conical irregular
spines increasing towards the poles; each polar spine surrounded by a
flame-shaped, circumpolar area of longer spines; all large spines (also the
polar spines) curved or contorted at one pole and much stronger and more
numerous than at the other; length variable, often equal to the longer
axis.
_Dimensions._--Longer axis of the shell 0.12, shorter axis 0.09; pores
0.005 to 0.015, bars 0.003 to 0.005; length of the polar spines 0.1 to
0.15.
_Habitat._--Western part of the Tropical Atlantic, Station 347, depth 2250
fathoms.
Genus 129. _Lithapium_,[168] n. gen.
_Definition._--#Ellipsida# with simple ellipsoidal or pear-shaped shell;
with a single spine only situated at one pole of the main axis.
The genus _Lithapium_ represents a peculiar modification of
_Ellipsoxiphus_; one of the two opposite polar spines disappears by
reduction, and in this way only a single spine remains, at one pole of the
main axis. For this reason the shell assumes a characteristic pear-shape,
and may easily be confounded with some similar Monocyrtida (_Halicapsa_).
1. _Lithapium pyriforme_, n. sp. (Pl. 14, fig. 9).
Proportion of the longer axis to the shorter = 6 : 5. Shell thin walled,
with regular, circular pores, four times as broad as the bars; six to eight
on the half equator. Surface a little thorny. The single polar spines
three-sided pyramidal, as broad at the base as one mesh, about as long as
the radius of the shell. (In the specimen figured, there was on the
opposite pole a little rudiment of the other lost polar spine; it is
missing in other specimens.)
_Dimensions._--Major axis of the ellipsoidal shell 0.12, minor axis 0.1;
pores 0.02, bars 0.005; length of the single polar spine 0.05, basal
thickness 0.02.
_Habitat._--Central area of the Pacific, Station 266, depth 2750 fathoms.
2. _Lithapium halicapsa_, n. sp. (Pl. 14, fig. 8).