Chapter XI: Literature and History (6)

The genus _Odontosphæra_ is distinguished from the foregoing _Acrosphæra_ by the peculiar disposition of the spines, which are not scattered on the outside of the shell between the pores, but so disposed that each larger pore is protected by one single spine, obliquely placed over it.

{102}1. _Odontosphæra monodon_, n. sp. (Pl. 5, fig. 5).

Shell spherical or subspherical, with very small and numerous circular pores, much smaller than the bars. Twelve to fifteen pores on the half meridian of the shell. Between them a variable number of larger roundish apertures (mostly twelve to sixteen) irregularly scattered, one-fourth to one-fifth as broad as the shell radius. On the margin of every larger aperture a single (rarely two or three) sharp conical tooth, about as long as the diameter of the aperture, and obliquely laid over them.

_Dimensions._--Diameter of the shell 0.1 to 0.13, of the pores 0.001 to 0.003, of the bars 0.01 to 0.02, of the larger apertures 0.01 to 0.02.

_Habitat._--Sunda Archipelago, Station 192, surface.

2. _Odontosphæra cyrtodon_, n. sp. (Pl. 5, fig. 6).

Shell spherical or subspherical, with numerous roundish pores of very irregular size and distribution, mostly larger than the bars. Ten to twelve pores on the half meridian of the shell. Between them a variable number (mostly six to nine) of large roundish pores, about half as broad as the shell radius, armed on one side of the margin with one single large tooth, about as long as the diameter of the aperture, hook-like, curved, and obliquely laid over them.

_Dimensions._--Diameter of the shell 0.12 to 0.14, of the pores 0.01 to 0.02, of the bars 0.003 to 0.006, of the larger apertures 0.03 to 0.04.

_Habitat._--Indian Ocean, near the Cocos Islands, Rabbe, surface.

Genus 35. _Choenicosphæra_,[57] n. gen.

_Definition._--#Collosphærida# with simple shells, armed on the outside with radial spines, forming elegant coronals around the larger pores.

The genus _Choenicosphæra_ is characterised by the peculiar disposition of its radial spines, which form protective coronals around the larger pores, or even around all pores of the shell.

Subgenus 1. _Choenicosphærula_.

_Definition._--A coronal of spines around every pore of the shell.

1. _Choenicosphæra murrayana_, n. sp. (Pl. 8, fig. 4).

Shell spherical, with large circular or roundish pores of unequal size, two to four times as broad as the bars. Ten to twelve pores in the half meridian of the shell. Margin of every pore {103}with a coronal of six to nine short and acute spines, not longer than the half diameter of the pore. No spines between the pores.

_Dimensions._--Diameter of the shell 0.16 to 0.2, of the pores 0.02 to 0.03; length of the spines 0.008 to 0.012.

_Habitat._--Færöe Channel (Gulf Stream), common. Expedition of H.M.S. "Triton," John Murray.

2. _Choenicosphæra flosculenta_, n. sp.

Shell spherical, with large circular or roundish pores of different size, three to six times as broad as the bars. Six to eight pores in the half meridian of the shell. Margin of every pore somewhat prominent, with a coronal of ten to twenty parallel acute spines of different length, the largest somewhat longer than the diameter of the pore. No spines between the pores.

_Dimensions._--Diameter of the shell 0.12 to 0.15, of the pores 0.02 to 0.04; length of the spines 0.02 to 0.05.

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

Subgenus 2. _Choenicosphærium_.

_Definition._--A coronal of spines only around the larger pores, not around the smaller.

3. _Choenicosphæra nassiterna_, n. sp. (Pl. 8, fig. 3).

Shell spherical, with circular or roundish pores of very different size. The smaller pores very numerous, without coronal of spines, roundish, about as broad as the bridges. Twenty to thirty pores in the half meridian of the shell. Between them, irregularly scattered, a small number (eight to twelve) of very large circular pores, one-third to one-half as broad as the radius of the shell, armed with a coronal of six to nine parallel, straight, acute spines, about half as long as the radius of the shell.

_Dimensions._--Diameter of the shell 0.1 to 0.13, of the smaller pores 0.002 to 0.004, of the larger armed pores 0.02 to 0.03; length of the spines 0.03 to 0.04.

_Habitat._--Philippine Islands, Mindanao, Station 213, depth 2050 fathoms.

4. _Choenicosphæra flammabunda_, n. sp. (Pl. 8, fig. 5).

Shell spherical, with circular or roundish pores of very different size. The smaller pores very numerous and unequal, very irregularly scattered, hardly one-fourth to one-half as broad as the bridges between them. Twelve to twenty-four pores in the half meridian of the shell. Between them, irregularly scattered, a variable number (ten to twenty) of very large circular pores, about one-fourth as broad as the radius of the shell. The margin of these large pores is armed with a very irregular coronal of four to twelve unequal, curved acute spines, partly simple, partly branched like {104}a deer-horn, one-fourth to one-half as long as the radius of the shell. Some other small spines irregularly scattered over the shell.

_Dimensions._--Diameter of the shell 0.12 to 0.16, of the smaller pores 0.001 to 0.004, of the larger armed pores 0.016 to 0.024; length of the spines 0.02 to 0.04.

_Habitat._--Central area of the Tropical Pacific, Stations 266 to 272, depth 2425 to 2925 fathoms.

Genus 36. _Siphonosphæra_,[58] J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 59.

_Definition._--#Collosphærida# with simple shells, the pores of which are prolonged into external simple radial tubuli with solid wall; outer mouth of the tubuli truncated, smooth.

The genus _Siphonosphæra_ is, next to _Collosphæra_, the most common of all Collosphærida, and rich in different species; all agreeing in the tubular prolongation of the pores, and corresponding therefore to _Ethmosphæra_ among the simple Liosphærida.

Subgenus 1. _Holosiphonia_, Haeckel.

_Definition._--All the pores or apertures of the shell prolonged into tubules.

1. _Siphonosphæra pansiphonia_, n. sp.

Shell a regular sphere, everywhere occupied by short, regular cylindrical tubes, all of the same size and form. Length of the tubules equal to their breadth and to the intervals between them. Ten to twelve tubules in the half meridian of the shell. This most regular species is nearly allied to _Collosphæra regularis_, and may be derived from it by tubular prolongation of all the regular pores.

_Dimensions._--Diameter of the shell 0.1 to 0.12, length and breadth of the tubules 0.005 to 0.006.

_Habitat._--Indian Ocean, Sunda Strait, Rabbe, surface.

2. _Siphonosphæra marginata_, n. sp.

Shell a regular or subregular sphere, occupied by numerous short cylindrical tubules of different sizes. Six to eight tubules in the half meridian of the shell. Diameter of the tubules about equal to their distance apart, but two to four times as large as their length.

_Dimensions._--Diameter of the shell 0.1 to 14; length of the tubules 0.004 to 0.006, breadth of the tubules and the intervals 0.01 to 0.02.

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

{105}3. _Siphonosphæra tubulosa_, J. Müller (Pl. 6, fig. 4).

_Siphonosphæra tubulosa_, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 59.

_Siphonosphæra tubulosa_, Haeckel, 1862, Monogr. d. Radiol., p. 532.

_Collosphæra tubulosa_, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 59.

_Thalassicolla punctata_, var., Huxley, 1851, Ann. and Mag. Nat. Hist.,
ser. 2, vol. viii. p. 435, pl. xvi. fig. 5.

Shell subspherical or roundish, somewhat irregular, occupied by a small number (five to ten) of short cylindrical tubules, irregularly scattered at great distances; intervals between the tubules very large, two to four times as broad as the length of the tubules, which is equal to their breadth and about one-fifth or one-sixth of the shell diameter. Only two or three tubules in the half meridian of the shell.

_Dimensions._--Diameter of the shell 0.12 to 0.15, length and breadth of the tubules 0.02 to 0.03.

_Habitat._--Equatorial zone of the Pacific, Stations 225, 265, 268, surface.

4. _Siphonosphæra cyathina_, n. sp. (Pl. 6, fig. 10).

Shell a regular sphere, everywhere occupied by short cup-like tubules of somewhat different size. In the half meridian of the shell about ten to twelve tubules, nearly cylindrical, but constricted in the middle. Inner and outer aperture of the tubule of the same size; their diameter equal to their length and distance.

_Dimensions._--Diameter of the shell 0.1 to 0.12, length and breadth of the tubules 0.005 to 0.01.

_Habitat._--West coast of Tropical Africa, Stations 348 to 352, surface.

5. _Siphonosphæra patinaria_, n. sp. (Pl. 6, figs. 7, 8).

Shell a regular or subregular sphere, occupied by numerous broad cup-like tubules of very different sizes. In the half meridian of the shell about six to eight tubules, very flat, circular or subcircular, much constricted in the middle. Diameter of the inner aperture larger than that of the middle stricture, smaller than that of the outer aperture of the tubule; outer diameter two to four times as great as their length.

_Dimensions._--Diameter of the shell 0.1 to 0.15, of the pores 0.01 to 0.04; length of the tubules 0.01, breadth 0.02 to 0.04.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.

6. _Siphonosphæra infundibulum_, n. sp.

Shell subspherical or irregular rounded, occupied by a small number (six to twelve) of large funnel-like tubules of very different size, scattered irregularly at great distances. Intervals between the tubules larger than their length, which surpasses the radius of the shell. Outer opening of the funnels three to four times as broad as the inner.

_Dimensions._--Diameter of the shell 0.15; length of the tubules 0.05 to 0.09.

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

{106}7. _Siphonosphæra conifera_, n. sp. (Pl. 6, fig. 9).

Shell subspherical, everywhere occupied by irregular conical tubules, the length of which nearly reaches the shell radius. Inner aperture of the cones two to three times as large as the outer. Four to five tubules in the half meridian of the shell. Distances between the bases of the cones small and irregular.

_Dimensions._--Diameter of the shell 0.06 to 0.08, length of the tubules 0.03 to 0.04; inner aperture of the cones 0.01 to 0.02, outer aperture 0.008 to 0.01.

_Habitat._--Indian Ocean, Cocos Islands, Rabbe, surface.

8. _Siphonosphæra fragilis_, n. sp.

Shell quite irregular roundish or nearly ovate, very thin and fragile, everywhere occupied by irregular, short, and broad cylindrical or conical tubes. Six to ten tubes in the half meridian of the shell. Diameter of the tubules about one-eighth that of the shell, three to four times as large as the length of the tubules, and the distance apart of their bases.

_Dimensions._--Diameter of the shell 0.16 to 0.24, of the tubules 0.02 to 0.03; length of the tubules 0.006 to 0.008, distance of them 0.005 to 0.009.

_Habitat._--East coast of Australia, Sydney, Faber; Station 165, surface.

Subgenus 2. _Merosiphonia_, Haeckel.

_Definition._--Only part of the shell apertures prolonged in tubules, the others simple.

9. _Siphonosphæra socialis_, n. sp. (Pl. 6, figs. 1, 2).

Shell a regular or subregular sphere, bearing only a small number (one to four, commonly two to three) of short and broad cylindrical tubules, irregularly scattered. Between them many small circular or subcircular pores of different sizes, double as broad as their bars. Eight to ten pores in the half meridian of the shell. Tubules three to six times as broad as the pores, about as long as broad, now quite cylindrical, now somewhat dilated at the outer opening. (Although the shells and cells of this common species are among the smallest, their colonies are among the largest, often containing more than one hundred social individuals, often enclosed in alveoles.)

_Dimensions._--Diameter of the shell 0.04 to 0.05, of the pores 0.002 to 0.004, of the tubules 0.015 to 0.02; length of them about the same.

_Habitat._--Tropical and subtropical part of the Eastern Atlantic, Cape Verde Islands, Canaries, very common, Haeckel; Stations 338 to 353, surface.

10. _Siphonosphæra polysiphonia_, n. sp.

Shell a regular or subregular sphere, bearing twelve to sixteen circular pores in its half meridian. Nearly one half the pores simple, very small; the other half prolonged into short cylindrical tubules, {107}half as long as broad, two to four times as broad as the pores and their intervals. This species is nearly related to the foregoing, which it represents in the western tropical part of the Atlantic, but differs constantly in the double size of the shell and the much larger number of the tubules.

_Dimensions._--Diameter of the shell 0.06 to 0.09, of the pores 0.002 to 0.004, of the tubules 0.01 to 0.012; their length 0.006 to 0.008, surface.

_Habitat._--Tropical and subtropical part of the Western Atlantic, coast of Brazil, &c., Rabbe.

11. _Siphonosphæra macrosiphonia_, n. sp.

Shell a regular sphere, with numerous very small pores of equal size and distribution. Twelve to sixteen pores in its half meridian. Bars (between the pores) three to four times as broad as their diameter. Only a small number (two to four) of very long cylindrical tubes, irregularly scattered, nearly as long or somewhat longer than the shell diameter; now quite straight, now somewhat curved. Diameter of the cylinders four to six times as large as that of the pores.

_Dimensions._--Diameter of the shell 0.1 to 0.12, of the pores 0.002 to 0.004, of the tubules 0.015 to 0.018; length of the tubules 0.08 to 0.16.

_Habitat._--Central Tropical Pacific, Station 266 to 272, surface.

12. _Siphonosphæra serpula_, n. sp. (Pl. 6, fig. 6).

Shell a regular sphere, with numerous very small pores of equal size and distribution. Eight to ten pores in its half meridian; bars between them three to four times as broad as their diameter. Only a small number (six to eight) of very long and snake-like, contorted, cylindrical tubes, irregularly scattered. The shape of the latter is very much like that of the calcareous tubes of some species of _Serpula_; they are nearly as long as, or longer than, the shell diameter, and four to six times as broad as the pores.

_Dimensions._--Diameter of the shell 0.12 to 0.14, of the pores 0.003 to 0.005, of the tubules 0.02 to 0.022; length of the tubules 0.1 to 0.2.

_Habitat._--North Eastern Pacific, Station 252 to 262, Sandwich Islands, Haltermann.

13. _Siphonosphæra chonophora_, n. sp. (Pl. 6, fig. 5).

Shell a regular or subregular sphere, with numerous very small pores of equal size and distribution, ten to twelve in its half meridian. Bars between the pores four to six times their diameter. Only a small number (two to six) of very large funnel-like tubules, irregularly scattered. The inner half of these tubules is a short cylindrical tube, of the same thickness as the shell, three to four times as broad as the pores; the outer half is an irregular funnel, suddenly expanded, with siliceous walls of the utmost tenuity and fragility, often irregularly folded and contorted, like a decayed flower-calyx, often half as large as the shell.

_Dimensions._--Diameter of the shell 0.1 to 0.12, of the pores 0.003 to 0.005, inner half of the tubules 0.015 to 0.02, outer funnel-like half 0.05 to 0.08.

_Habitat._--South Pacific, Stations 285 to 295, surface.

{108}14. _Siphonosphæra pipetta_, n. sp. (Pl. 6, fig. 3).

Shell more or less irregularly roundish or subspherical, occupied in part by very small pores, in part by very large cylindrical tubules, inflated in the middle. Number, form, and size of the tubes very irregular; commonly there are five to ten, half as long or as long as the shell radius; their inner and outer aperture about half as broad as their inflated middle part; three to nine times as broad as the pores. A very irregular and variable species.

_Dimensions._--Diameter of the shell 0.1 to 0.15, of the pores 0.001 to 0.005, of the tubules 0.015 to 0.03; length of the tubules 0.03 to 0.08.

_Habitat._--North Pacific, Stations 242 to 253, surface.

Genus 37. _Mazosphæra_,[59] Ehrenberg, 1860.

_Mazosphæra_, Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss.
Berlin, p. 833.

_Definition._--#Collosphærida# with simple shells, the pores of which are prolonged into external simple radial tubuli with solid wall; outer mouth of each tubulus armed with a single tooth.

The genus _Mazosphæra_ is intermediate between _Siphonosphæra_ and _Odontosphæra_, agreeing with the former in the tubular prolongation of the pores, with the latter in the possession of a single large protective tooth on the outer opening.

1. _Mazosphæra hippotis_, n. sp. (Pl. 5, fig. 8).

Shell spherical, with circular pores of irregular size and distribution, scarcely half as broad as the bars; fifteen to twenty on the half meridian of the shell. Between them, irregularly distributed, a variable number (ten to fifteen) of short cylindrical radial tubules, about twice as long as broad, and half as long as the shell radius. Mouth of the tubuli obliquely truncated, having on one side a strong acute tooth.

_Dimensions._--Diameter of the shell 0.11 to 0.12, of the pores 0.002 to 0.004, of the bridges 0.006 to 0.009; length of the tubuli 0.03, breadth of them 0.01 to 0.015.

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

2. _Mazosphæra lagotis_, n. sp. (Pl. 5, fig. 9).

Shell spherical, with circular pores of irregular size and distribution, about as broad as the bars; twelve to sixteen on the half meridian. Between them, irregularly distributed, a variable number (eight to twelve) of long, cylindrical, curved tubules, three to six times as long as broad, and about as long as the shell radius; their external mouth lateral, obliquely truncated, ovate, having on one side a strong conical tooth.

{109}_Dimensions._--Diameter of the shell 0.1 to 0.12, of the pores 0.002 to 0.01; length of the tubuli 0.05 to 0.07.

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

3. _Mazosphæra lævis_, Ehrenberg.

_Mazosphæra lævis_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 297, Taf. vii. fig. 7.

Shell spherical, with very small pores, scarcely one-fourth as broad as the bars. Fifteen to twenty pores on the half meridian of the shell. Between them, irregularly distributed, a variable number (fifteen to twenty) of short conical tubules, about as long as broad, only one-fifth to one-sixth as long as the shell radius. Mouth of the tubuli truncated, with an obtuse short tooth on one side.

_Dimensions._--Diameter of the shell 0.08 to 0.09, of the pores 0.001 to 0.002, of the bridges 0.005 to 0.008; length of the tubuli 0.01 to 0.02, breadth of them the same.

_Habitat._--Philippine Islands (depth 3300 fathoms), Ehrenberg; Station 206, depth 2100 fathoms; Station 225, depth 4575 fathoms.

4. _Mazosphæra apicata_, Ehrenberg.

_Mazosphæra apicata_, Ehrenberg, 1872, Monatsber. d. k. preuss. Akad. d.
Wiss. Berlin, p. 316.

Shell spherical, without small pores, only with a variable number (ten to twenty) of short conical tubules, twice as long as broad, and half as long as the shell radius. Mouths of the tubuli obliquely truncated, with a strong acute tooth on one side. (This species differs from the two preceding by the want of the small pores between the tubules.)

_Dimensions._--Diameter of the shell 0.08 to 0.1, of the tubules 0.01.

_Habitat._--Philippine Islands (depth 3300 fathoms), Ehrenberg; north coast of New Guinea, depth 2000 fathoms; Station 217.

Genus 38. _Trypanosphæra_,[60] n. gen.

_Definition._--#Collosphærida# with simple shells, the pores of which are prolonged into external simple radial tubuli with solid walls; outer mouth of each tubulus armed with a coronal of spines.

The genus _Trypanosphæra_ is intermediate between _Siphonosphæra_ and _Choenicosphæra_ agreeing with the former in the tubular prolongation of the pores, with the latter in the possession of a coronal of teeth on their outer opening.

Subgenus 1. _Trypanosphærula_, Haeckel.

_Definition._--All pores of the shell prolonged into short coronated tubules.

{110}1. _Trypanosphæra trepanata_, n. sp. (Pl. 5, fig. 4).

Shell regular spherical, with regular circular pores of nearly equal size, at unequal distances, one to four times as broad as the bars. Eight to ten pores on the half meridian. All the pores prolonged into short cylindrical tubuli about as long as broad, armed on the external mouth with an elegant coronal of twenty to thirty straight bristle-shaped, parallel teeth.

_Dimensions._--Diameter of the shell 0.12 to 0.14, of the pores 0.015 to 0.02; length of the tubuli 0.02.

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

2. _Trypanosphæra dentata_, n. sp.

Shell regular spherical, with regular circular pores of equal size, but at very different distances. Only three to four pores on the half meridian. All the pores prolonged into irregular curved, cylindrical tubuli, about as long as the shell radius, with a coronal of ten to twelve short conical teeth on the distal end.

_Dimensions._--Diameter of the shell 0.08 to 0.09; length of the tubuli 0.04, breadth 0.02.

_Habitat._--Central Pacific, Station 274, depth 2750 fathoms.

Subgenus 2. _Trypanosphærium_, Haeckel.

_Definition._--Only part of the shell-pores prolonged into coronated tubules.

3. _Trypanosphæra coronata_, n. sp. (Pl. 5, fig. 3).

Shell regular spherical, with irregular roundish pores of very different sizes. On the half meridian four to six large and twelve to sixteen very small pores. About half of the large pores prolonged into short cylindrical tubuli, the outer mouth of each being armed with an elegant coronal of ten to twenty thin irregular teeth.

_Dimensions._--Diameter of the shell 0.1 to 0.12, of the large pores 0.01 to 0.02, of the small pores 0.001; length of the tubuli 0.012.

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

4. _Trypanosphæra terebrata_, n. sp.

Shell irregular roundish, with unequal, small, roundish pores. Sixteen to twenty pores on the half meridian. Six to eight larger pores are prolonged into curved cylindrical tubuli, about as long as the shell radius, with a coronal of ten to twelve strong conical straight teeth on the distal end.

_Dimensions._--Diameter of the shell 0.15, of the pores 0.001 to 0.003; length of the tubuli 0.08, breadth 0.02.

_Habitat._--West Tropical Pacific, Station 225, depth 4575 fathoms.

{111}5. _Trypanosphæra transformata_, n. sp. (Pl. 5, figs. 1, 2).

Shell quite irregular, of very variable, roundish, or polyhedral form, with small irregular roundish pores, two to four times as broad as the bars. Ten to thirty on the half meridian. The different form of the shell depends upon the variable number of tubuli, which arise at irregular distances from the shell; commonly three to four, often also five to six, more rarely one or two. The tubuli are now more conical, now more cylindrical, about as long as the shell radius, at other times scarcely one-half or one-third as long, with a coronal of ten to twenty more or less curved teeth on the narrower distal mouth. All the different forms are to be found in one and the same colony, as shown in fig. 1. This coenobium, which I observed living in Ceylon, exhibited the same peculiar formation as I figured in _Collosphæra huxleyi_ in my Monograph 1862 (Taf. xxxiv. fig. 1). In the centre of the jelly-sphere lies a large globular alveole, surrounded by numerous small, young central capsules without shell; whilst in the surface lies one layer of older capsules, enclosed in shells. Some of the younger capsules exhibit self-division.

_Dimensions._--Diameter of the shells 0.08 to 0.12, pores 0.002 to 0.006; length and breadth of the tubuli 0.03 to 0.05.

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

Genus 39. _Caminosphæra_,[61] n. gen.

_Definition._--#Collosphærida# with simple shells, the pores of which are prolonged into external branched radial tubuli with solid wall.

The genus _Caminosphæra_ differs from _Siphonosphæra_ (and from all other Collosphærida) in the ramification of the tubuli, which arise from the pores; the walls of the tubuli are solid, not fenestrated.

1. _Caminosphæra furcata_, n. sp.

Shell spherical or subspherical, with a variable number (four to eight) of short cylindrical tubes, irregularly scattered, about as long as the radius of the shell. Every tube forked, with two cylindrical branches of the same size as the simple basal part of the tube. Mouth of the branches truncated, not dilated. Pores of the shell between the tubes very small, all of the same size, half as broad as their bars. Fifteen to twenty pores in the half meridian of the shell.

_Dimensions._--Diameter of the shell 0.1 to 0.12, of the pores 0.001 to 0.002; length of the tubules 0.05 to 0.06, breadth of them 0.012 to 0.015.

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

2. _Caminosphæra elongata_, n. sp.

Shell spherical, with a large number (twelve to twenty) of long cylindrical tubes, irregularly formed and scattered, somewhat longer than the diameter of the shell. Every tube forked at {112}the distal end, with two or three short irregular branches of unequal size and form; branches much shorter than the undivided basal part of the tube. Mouth of the branches narrowed, truncated. Pores of the shell between the tubes about half as broad, irregularly roundish or polygonal, two to three times as broad as their bars. Ten to twelve pores in the half meridian of the shell.

_Dimensions._--Diameter of the shell 0.05 to 0.07, of the pores 0.006 to 0.009; length of the tubules 0.06 to 0.09, breadth of them 0.015 to 0.02.

_Habitat._--Tropical Central Pacific, Station 271, depth 2425 fathoms.

3. _Caminosphæra dichotoma_, n. sp. (Pl. 7, fig. 2).

Shell spherical, with a variable number (ten to fifteen) of cylindrical tubes, irregularly scattered, about as long as the radius of the shell. Every tube furcated, with two cylindrical branches of the same size as the simple basal part of the tube. Mouth of the branches dilated, funnel-like, twice as broad as the tube; the edges irregularly dentated or lacerated. Pores between the tubes small, one-third to one-sixth as broad as these, half as broad as their bars. Ten to twelve pores in the half meridian of the shell.

_Dimensions._--Diameter of the shell 0.12 to 0.14, of the pores 0.003 to 0.005; length of the tubules 0.06 to 0.08, breadth of them 0.02 to 0.03.

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

4. _Caminosphæra dendrophora_, n. sp. (Pl. 7, fig. 1).

Shell spherical, with a variable number (eight to twelve) of long cylindrical tubes, irregularly branched and scattered, nearly as long as the diameter of the shell. Every tube with two to six (commonly three to four) branches of different sizes. Mouth of the branches dilated, funnel-like; the edges irregularly dentated or lacerated. Pores between the tubes half as broad as these, irregularly roundish, twice as broad as their bars. Ten to twelve pores in the half meridian of the shell.

_Dimensions._--Diameter of the shell 0.12 to 0.15, of the pores 0.006 to 0.01; length of the tubules 0.1 to 0.13, breadth of them 0.02 to 0.025.

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

Genus 40. _Solenosphæra_,[62] n. gen.

_Definition._--#Collosphærida# with simple shells, the pores of which are prolonged into external simple radial tubuli with fenestrated wall; outer mouth of the tubuli truncated, smooth.

The genus _Solenosphæra_ differs from _Siphonosphæra_ in the fenestration of the external radial tubes. A large number of shells, appertaining to this genus, were already described by Ehrenberg, and disposed in five different genera corresponding to the {113}different numbers of the tubuli:--_Disolenia_ with two tubes, _Trisolenia_ with three tubes, _Tetrasolenia_ with four tubes, _Pentasolenia_ with five tubes, _Polysolenia_ with six or more tubes. All these five genera are without value, as those different numbers of tubes occur frequently intermingled in the individual cells of one and the same colony, wherever the form and structure of the tubes is inherited with sufficient constancy to determine the species.

Subgenus 1. _Solenosphactra_, Haeckel.

_Definition._--Tubuli of the shell cylindrical or nearly cylindrical, the outer and inner apertures nearly of the same size.

1. _Solenosphæra variabilis_, Haeckel.

_Tetrasolenia quadrata_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
Berlin, Taf. x. fig. 20.

Shell quite irregular roundish or polyhedral, with roundish pores of different size. Ten to fifteen pores in the half meridian of the shell, two to three times as broad as the bars. Porous tubuli of the shell in variable number (in one and the same colony), three to nine, mostly four to six; cylindrical or subcylindrical or somewhat conical, two to three times as broad as long, not longer than the half radius of the shell. Inner aperture of the tubuli commonly as broad as the half radius of the shell (or somewhat smaller), about as large as the truncated outer aperture. This species is closely related to _Collosphæra polyedra_ (p. 97), and may be derived from it by a short tube-like prolongation of the larger apertures.

_Dimensions._--Diameter of the shell 0.1 to 0.16, of the pores 0.005 to 0.015; length of the tubules 0.02 to 0.03, breadth of them 0.04 to 0.06.

_Habitat._--Central area of the Tropical Pacific, Stations 270, 271, 272, depths 2425 to 2925 fathoms.

2. _Solenosphæra pandora_, n. sp. (Pl. 7, figs. 10, 11).

Shell irregular roundish or subglobular, with roundish pores of different sizes, mostly somewhat broader than the bars. About twelve to sixteen pores on the half meridian of the shell. Porous tubuli of the shell of variable number (in one and the same colony), one to six, mostly three to four; cylindrical or nearly cylindrical, somewhat longer than broad, not longer than the radius of the shell. Inner aperture of the tubuli commonly as broad as the half radius of the shell, and a little smaller than the truncated outer aperture.

_Dimensions._--Diameter of the shell 0.07 to 0.1, of the pores 0.003 to 0.006; length of the tubuli 0.03 to 0.05, breadth of them 0.02 to 0.03.

_Habitat._--Central area of the Tropical Pacific, Stations 266 to 274, depths 2350 to 2925 fathoms.

{114}3. _Solenosphæra megalactis_, Haeckel.

_Trisolenia megalactis_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 301, Taf. viii. fig. 19.

Shell irregularly polyhedrical, with very small roundish pores, scarcely half as broad as the bars. Only eight to ten pores on the half meridian of the shell. Porous tubuli of the shell of variable number (in one and the same colony), two to five, mostly three or four; cylindrical, about as long as the radius of the shell. Inner aperture of the tubuli commonly as broad as the half radius of the shell, and quite as broad as the truncated outer aperture.

_Dimensions._--Diameter of the shell 0.07 to 0.09, of the pores 0.002 to 0.004, of the bars 0.005 to 0.009; length of the tubuli 0.03 to 0.04, breadth of them 0.02.

_Habitat._--Pacific; California, Philippine Sea, Ehrenberg; Stations 256 to 285, depths 310 to 3000 fathoms.

4. _Solenosphæra serpentina_, n. sp. (Pl. 7, fig. 7).

Shell nearly spherical, with very small circular pores, scarcely one-third or one-fourth as broad as the bars. Only five to seven pores in the half meridian of the shell. Porous tubuli of the shell of variable number (in one and the same colony), two to nine, mostly seven or eight; cylindrical, somewhat curved or contorted, once and a half or twice as long as the diameter of the shell, with few very small and widely scattered pores. Inner and outer aperture of the tubuli have the same diameter, about one-fifth or one-fourth that of the shell. (This species is closely allied to _Siphonosphæra serpula_, but is distinguished from it by the long tortuous tubuli and the small scarce pores.)

_Dimensions._--Diameter of the shell 0.08 to 0.1, of the pores 0.001 to 0.002, of the bars 0.004 to 0.008; length of the tubuli 0.12 to 0.18, breadth of them 0.02 to 0.025.

_Habitat._--North-eastern Pacific, between Sandwich Islands and California, Haltermann, surface.

Subgenus 2. _Solenosphenia_, Haeckel.

_Definition._--Tubuli of the shell more or less conical, the inner aperture much larger than the outer aperture.

5. _Solenosphæra venosa_, Haeckel.

_Tetrasolenia venosa_, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss.
Berlin, p. 301, Taf. vii. fig. 22.

Shell irregular polyhedral or roundish, with a delicate network of large irregular polyhedral meshes, five to ten times as broad as the thin bars. Eight to twelve meshes on the half meridian of the shell. Fenestrated tubuli of the shell of variable number (in one and the same colony), one to five, commonly three or four, shaped like a short truncated cone, about half as long as broad on its base, shorter than the radius of the shell. Inner aperture of the cone nearly as broad as the half radius of the shell, about twice as broad as the truncated outer aperture.

{115}_Dimensions._--Diameter of the shell 0.07 to 0.12, of the pores 0.008 to 0.016, of the bars 0.001; length of the tubuli 0.02 to 0.03, inner aperture 0.03 to 0.04, outer aperture 0.02 to 0.03.

_Habitat._--Indian Ocean, Sunda Strait, Rabbe.

6. _Solenosphæra ascensionis_, n. sp. (Pl. 7, fig. 9).

Shell somewhat irregular, subspherical, with polygonal pores of different size. Twelve to fifteen pores in the half meridian of the shell, two to eight times as broad as their bars. Porous tubuli of the shell of variable number (in one and the same colony), three to nine, mostly five to seven; conical or nearly cylindrical, irregular, about as long as broad at their base. Inner aperture of the tubuli two to four times as broad as the broadest pores, and double as broad as the truncated circular outer aperture.

_Dimensions._--Diameter of the shell 0.1 to 0.12, of the pores 0.004 to 0.018, of the bars 0.002, length of the tubuli 0.04, inner aperture 0.04, outer 0.02.

_Habitat._--South Atlantic, near Ascension Island, Station 343, surface.

Subgenus 3. _Solenosphyra_, Haeckel.

_Definition._--Tubuli of the shell funnel-like, the outer aperture much larger than the inner.

7. _Solenosphæra cornucopia_, n. sp. (Pl. 7, fig. 8).

Shell spherical or subspherical, with roundish pores of different size. Ten to twelve pores in the half meridian of the shell, two to three times as broad as the bars. Porous tubuli of the shell of variable number (in one and the same colony), four to eight, mostly five to seven, funnel-like, about as long as the diameter of the shell. Inner aperture of the tubuli commonly two-thirds or three-fourths as broad as the radius of the shell (or somewhat smaller), only one-half or two-thirds as broad as the dilated and truncated outer aperture.

_Dimensions._--Diameter of the shell 0.07 to 0.09, of the pores 0.006 to 0.018; length of the tubuli 0.06 to 0.08, diameter of the inner aperture 0.04 to 0.05, of the outer 0.06 to 0.08.

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

8. _Solenosphæra amalthea_, n. sp.

Shell irregular roundish or spherical, with small circular pores of different size. Fifteen to twenty pores in the half meridian of the shell, but still not as broad as the bars. Porous tubuli of the shell of variable number (in one and the same colony), three to six, commonly four or five, funnel-like, about as long as the radius of the shell. Inner aperture of the tubuli about half as broad as the radius of the shell, only one-half or one-third as broad as the truncated outer aperture. (This species is intermediate between the preceding and _Siphonosphæra chonophora_, Pl. 6, fig. 5.)

{116}_Dimensions._--Diameter of the shell 0.09 to 0.11, of the pores 0.002 to 0.004, of the bars 0.003 to 0.006; length of the tubuli 0.05 to 0.06; diameter of the inner aperture 0.02 to 0.03, of the outer aperture 0.05 to 0.07.

_Habitat._--Western part of the South Atlantic, Station 325, surface.

Genus 41. _Otosphæra_,[63] n. gen.

_Definition._--#Collosphærida# with simple shells, the pores of which are prolonged into external simple radial tubuli with fenestrated walls; outer mouth of the tubuli armed with a single tooth.

The genus _Otosphæra_ differs from _Solenosphæra_ by the single tooth on the external mouth of the tubuli, from _Mazosphæra_ by the fenestration of the walls of the tubuli.

1. _Otosphæra polymorpha_, n. sp. (Pl. 7, fig. 6).

Shell quite irregular, polyhedral or roundish, very variable in size and form, with numerous very small pores, much smaller than the bars. Twenty to thirty pores in the half meridian of the shell. Porous tubuli of the shell commonly in variable number (one to four), but sometimes constant in number (one, two, three, or four) in the one and same colony. Tubuli irregular conical, commonly about as long as the radius of the shell; their outer aperture obliquely truncated, on one side prolonged into one large, prominent, bill-like, curved, acute tooth.

_Dimensions._--Diameter of the shell 0.12 to 0.15, of the pores 0.001 to 0.002; length of the tubuli 0.06 to 0.08, inner aperture 0.03, outer aperture 0.02.

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

2. _Otosphæra auriculata_, n. sp. (Pl. 7, fig. 5).

Shell quite irregular, of extremely variable form, now inclining to roundish, now to polyhedral, with very numerous small pores, irregularly formed and distributed. Twelve to twenty-four pores in the half meridian of the shell, of very different size, for the most part larger than the bars. Porous tubuli of the shell of variable number (in one and the same colony), one to five, mostly three or four, of conical form, irregularly formed and scattered, commonly about half as long as the radius of the shell. Outer aperture of the tubuli obliquely truncated, with one large prominent, often curved, acute tooth.

_Dimensions._--Diameter of the shell 0.1 to 0.2, of the pores 0.003 to 0.005; length of the tubuli 0.01 to 0.05, inner aperture 0.04, outer aperture 0.03.

_Habitat._--Central Tropical Pacific, Stations 268 to 272, depths 2425 to 2925 fathoms.

{117}Genus 42. _Coronosphæra_,[64] n. gen.

_Definition._--#Collosphærida# with simple shells, the pores of which are prolonged into external simple radial tubuli with fenestrated walls; outer mouth of the tubuli armed with a coronal of spines.

The genus _Coronosphæra_ differs from _Solenosphæra_ by the coronated mouth of the tubuli, from _Trypanosphæra_ by the fenestration of the walls of the tubuli.

1. _Coronosphæra diadema_, n. sp. (Pl. 7, fig. 3).

Shell spherical or subspherical, with a variable number (fifteen to twenty) of short, coronal-like tubules, irregularly scattered, about half as long as the radius of the shell. Outer aperture of the tubuli irregularly dentated, a little dilated, and not much broader than the inner aperture, one-half or one-third as broad as the shell radius. Pores of the shell and of the tubuli circular or roundish, very irregularly scattered, mostly one-half or one-third as broad as the bars.

_Dimensions._--Diameter of the shell 0.11 to 14, of the pores 0.002 to 0.004, of the bars 0.006 to 0.012; length of the tubuli 0.03, inner aperture 0.02 to 0.03, outer aperture 0.03 to 0.04.

_Habitat._--Central Pacific, Stations 268 to 270, depths 2550 to 2925 fathoms.

2. _Coronosphæra calycina_, n. sp. (Pl. 7, fig. 4).

Shell spherical or subspherical, with a variable number (eight to twelve) of large, funnel-like tubules, irregularly scattered, about as long as the radius of the shell. Outer aperture of the tubuli irregularly dentated, much dilated, somewhat broader than the shell radius, three to four times as broad as the inner circular aperture. Pores of the shell and of the tubuli circular or roundish, of very different size, one to three times as broad as the bars.

_Dimensions._--Diameter of the shell 0.1 to 0.3, of the pores 0.003 to 0.01, of the bars 0.002 to 0.004; length of the tubuli 0.1, inner aperture 0.02 to 0.03, outer aperture 0.06 to 0.18.

_Habitat._--Central Pacific, Stations 271, 272, depths 2425 and 2600 fathoms respectively.

3. _Coronosphæra convolvulus_, n. sp.

Shell irregular roundish, with a variable number (five to ten) of long, curved tubules, about as long as the shell diameter. The inner half of the tubuli is narrow, cylindrical; the outer half funnel-like dilated, similar to the flower of _Convolvulus_. The outer aperture is elegantly dentated, five to six times as broad as the inner aperture. Pores of the shell and of the tubuli very irregular roundish, about as broad as the bars.

_Dimensions._--Diameter of the shell 0.08 to 0.09, of the pores and bars 0.004 to 0.008; length of the tubuli 0.07 to 0.1, inner aperture 0.01, outer aperture 0.05.

_Habitat._--Tropical Atlantic, Station 347, surface.

{118}Subfamily CLATHROSPHÆRIDA, Haeckel, 1881, Prodromus, p. 472.

_Definition._--#Collosphærida# with a double lattice-shell around every central capsule of the coenobium; both concentric shells connected by irregular or subradial beams, commonly solid or lamellar staffs, rarely hollow tubes.

Genus 43. _Clathrosphæra_,[65] Haeckel, 1881, Prodromus, p. 472.

_Definition._--#Collosphærida# with a double lattice-shell around every central capsule of the coenobium; surface of the outer shell smooth.

The genus _Clathrosphæra_ (with smooth surface) and the following _Xanthiosphæra_ (with spiny surface) form together the small subfamily, Clathrosphærida, different from the other Collosphærida by the double lattice-shell. From the surface of the inner primary shell arise either solid spines or hollow tubes, which unite by the anastomosis of irregular branches and so form the outer secondary shell, often very incomplete and irregular. All Clathrosphærida seem to inhabit great depths.

Subgenus 1. _Clathrosphærula_, Haeckel.

_Definition._--The connecting staffs between both shells are hollow tubes (derived from _Siphonosphæra_).

1. _Clathrosphæra circumtexta_, n. sp. (Pl. 8, fig. 6).

Inner shell spherical, with irregular roundish large meshes, now broader now smaller than their bars. Eight to ten meshes in the half meridian of the shell. All these meshes are prolonged into short cylindrical hollow tubes, about as long as broad, somewhat constricted in the middle. From the margins of the outer openings of these tubes proceed very numerous and delicate siliceous filaments, which all lie on the same spherical face, branch, anastomose, and twine over the openings and the intervals between them, forming a very thin, arachnoid spherical outer shell. The meshes of this are quite irregular polygonal, of very different size and form. The radius of the inner shell bears to that of the outer a ratio = 5 : 6.

_Dimensions._--Diameter of the inner shell 0.11 to 0.13, of the outer 0.13 to 0.16; meshes of the inner shell 0.005 to 0.02, of the outer 0.005 to 0.04.

_Habitat._--North Pacific, Stations 238 to 253, depths 2050 to 3950 fathoms.

Subgenus 2. _Clathrosphærium_, Haeckel.

_Definition._--The connecting staffs between the two shells are solid rods or lamellar spines (derived from _Acrosphæra_).

{119}2. _Clathrosphæra arachnoides_, n. sp. (Pl. 8, fig. 7).

Inner shell spherical, with irregular roundish meshes, two or three times as broad as the bars. Ten to twelve meshes in the half meridian of the shell. From its surface arise numerous conical radial spines (with base often fenestrated), which at equal distances from the surface send out lateral branches. All these branches lie on a spherical face, and form by communications the irregular, very delicate, arachnoid network of the outer shell, quite unlike that of the inner, with large polygonal meshes of very different size. Eight to sixteen meshes in the half meridian of the shell. Surface of the outer shell nearly spherical, somewhat uneven, like a spider's web. The radius of the inner shell bears to that of the outer a ratio = 3 : 4.

_Dimensions._--Diameter of the inner shell 0.12 to 0.14, of the outer 0.15 to 0.18; pores of the inner shell 0.003 to 0.02, of the outer 0.01 to 0.04.

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

3. _Clathrosphæra lamellosa_, n. sp. (Pl. 8, fig. 8).

Inner shell spherical or subspherical, with irregular roundish meshes, about half as broad as the bars. Twelve to sixteen meshes in the half meridian of the shell. From its surface arise numerous oblique irregular staffs or broad and thin lamellæ, which branch quite irregularly, and by communications of the branches form the thin outer shell. This is quite irregular roundish or subspherical, very unlike the inner, with large polygonal meshes of different size, six to twelve in the half meridian of the shell. Bridges between the meshes very variable, now very thin filamentous, now very broad lamellar. Outer surface very uneven or tuberculated, but not spinous. The radius of the inner shell bears to that of the outer a ratio = 5 : 6.

_Dimensions._--Diameter of the inner shell 0.1 to 0.13, of the outer 0.12 to 0.18; pores of the inner shell 0.003 to 0.009, of the outer 0.01 to 0.04.

_Habitat._--Central area of the Tropical Pacific, Stations 270 to 274, depths 2350 to 2925 fathoms.

Genus 44. _Xanthiosphæra_,[66] Haeckel, 1881, Prodromus, p. 472.

_Definition._--#Collosphærida# with a double lattice-shell around every central capsule of the coenobium; surface of the outer shell thorny or spiny.

The genus _Xanthiosphæra_ differs from the foregoing _Clathrosphæra_ by spines or thorns arising from the surface of the outer shell, commonly very irregular.

1. _Xanthiosphæra capillacea_, n. sp.

Inner shell spherical, with irregular polygonal meshes, three to five times as broad as their narrow bars. Six to eight meshes in the half meridian of the shell. From its surface arise at the nodes of the network numerous thin radial spines, which, at equal distances from the surface, {120}send out lateral branches. All these branches lie on a spherical face, and form by communications the irregular delicate network of the outer shell, very like that of the inner, with large polygonal meshes, six to eight meshes in the half meridian of the shell. Surface of the outer shell covered with numerous straight spines, prolongations of the inner spines, but only half as long as these. The radius of the inner shell bears to that of the outer a ratio = 3 : 5.

_Dimensions._--Diameter of the inner shell 0.1 to 0.12, of the outer 0.15 to 0.19; pores of the inner shell 0.02 to 0.04 to 0.06, of the outer 0.04 to 0.06 to 0.08; length of the outer spines 0.01 to 0.02.

_Habitat._--Central area of the Tropical Pacific, Station 263, depth 2650 fathoms.

2. _Xanthiosphæra erinacea_, n. sp. (Pl. 8, fig. 9).

Inner shell spherical, with irregular roundish meshes, one-half to two times as broad as the bars. Fifteen to twenty meshes in the half meridian of the shell. From its surface arise numerous thin radial spines, which at equal distances from the surface send out lateral branches. All these branches lie on the face of a sphere, and form by communications the irregular delicate network of the outer shell, very unlike that of the inner, with large polygonal meshes, twelve to twenty-four in the half meridian of the shell. Surface of the outer shell covered with numerous straight spines, prolongations of the inner spines, and of the same length. The radius of the inner shell bears to that of the outer a ratio = 3 : 4.

_Dimensions._--Diameter of the inner shell 0.1 to 0.12, of the outer 0.13 to 0.16; pores of the inner shell 0.002 to 0.008, of the outer 0.01 to 0.03; length of the outer spines 0.02 to 0.03.

_Habitat._--Central area of the Tropical Pacific, Stations 270, 272, depth 2925 and 2600 fathoms respectively.

3. _Xanthiosphæra lappacea_, n. sp. (Pl. 8, figs. 10, 11).

Inner shell spherical or subspherical, with very small roundish pores, quite irregularly scattered, one-fourth to three-fourth as broad as their bars. Ten to twenty pores in the half meridian of the shell. From its surface arise in an extremely irregular and variable manner numerous oblique spines, often curved, often lamellar, and perforated by pores, sometimes hollow, fenestrated cones. At different distances from the surface these spines send out lateral curved branches, which by communications form the delicate and very irregular network of the outer shell. This network is often incomplete and very unlike that of the inner shell, with large polygonal meshes, six to eighteen in the half meridian of the shell. Surface of the outer shell covered with numerous small, curved, and oblique spines, prolongations of the inner spines, but scarcely one-third to one-half as long as these. The radius of the inner shell bears to that of the outer a ratio = 3 : 4.

_Dimensions._--Diameter of the inner shell 0.08 to 0.12, of the outer 0.11 to 0.15; pores of the inner shell 0.001 to 0.009, of the outer 0.01 to 0.04; length of the outer spines 0.005 to 0.009.

_Habitat._--Central area of the Tropical Pacific, Stations 263 to 274, depths 2350 to 3000 fathoms.

{121}Family VII. #STYLOSPHÆRIDA#, Haeckel (Pls. 13-17).

_Stylosphærida_, Haeckel, 1881, Prodromus, p. 449.

_Definition._--#Sphæroidea# with two radial spines on the surface of the spherical shell, opposite in one axis; living solitary (not associated in colonies).

The family #Stylosphærida# comprises a large number of very common #Sphæroidea#, and is distinguished from all others by the possession of two radial spines which are placed in one axis of the spherical shell.[67] By the expression of this "main axis" as a solid rod they form the transition to the #Prunoidea#, in which the whole shell is more or less transformed according to this "monaxial growth." But in these latter the shell, as well as the central capsule, becomes ellipsoidal, prolonged in one axis, whilst in the former they remain spherical. However, the distinction of both nearly allied groups is sometimes difficult.

The most simple Stylosphærida are the _Xiphostylida_, with one single spherical lattice-shell. To this ancestral group all other subfamilies can be opposed as "Stylosphærida concentrica," as their carapace is composed of two or more concentric lattice-shells: two in the Sphærostylida, three in the Amphistylida, four in the Cromyostylida, five or more in the Caryostylida. In all these four subfamilies the concentric shells are simple (not spongy) fenestrated spheres. In a sixth subfamily, in the Spongostylida, the shell is wholly or partially composed of a spongy irregular wicker-work, with or without a medullary shell in the centre.

Both the radial spines in all Stylosphærida are opposed normally in one axis; but in many species besides the normal form occur individual abnormalities, in which the two spines are not accurately opposed in this main axis, but placed in two different axes, intersecting at a smaller or larger angle. In the majority of the Stylosphærida both opposite spines have the same size and form; but in some genera they are more or less different, often in a very striking degree. The same differences occur in the nearly allied groups of #Prunoidea#, in the Ellipsida and Druppulida.

The distal ends of both spines are commonly free; but in the small group of Saturnalida (_Saturnalis_ with one single shell, _Saturnulus_ with two concentric shells, _Saturninus_ with three concentric shells) the distal ends of both spines are united, at equal distances from the centre, by a circular or elliptical ring. This remarkable peculiarity occurs in no other group of #Sphæroidea#, and consequently brings the Saturnalida into close relation with the #Discoidea#.

{122}_Synopsis of the Genera of Stylosphærida._

{ {Both spines
{Polar spines { equal, 45. _Xiphosphæra_.
{ free, without{
I. Subfamily { connecting {Spines
Xiphostylida. { ring on the { different
(Spherical shell{ distal ends. { in size
simple.) { { or form, 46. _Xiphostylus_.
{
{Both polar spines united by
{ a circular or elliptical
{ ring, 47. _Saturnalis_.

{ {Both spines
{ { equal, 48. _Stylosphæra_.
{Polar spines {
II. Subfamily { free. {Spines
Sphærostylida.{ { different in
(Two concentric { { size or
spheres.) { { form, 49. _Sphærostylus_.
{
{Both polar spines united by
{ a circular or elliptical
{ ring, 50. _Saturnulus_.

{ {Both spines
{ { equal, 51. _Amphisphæra_.
{Polar spines {
III. Subfamily { free. {Spines
Amphistylida. { { different in
(Three { { size or
concentric { { form, 52. _Amphistylus_.
spheres.) {
{Both polar spines united by
{ a circular or elliptical
{ ring, 53. _Saturninus_.

IV. Subfamily } {Both spines
Cromyostylida.}Polar spines { equal, 54. _Stylocromyum_.
(Four concentric} free. {
spheres.) } {Spines
} { different, 55. _Cromyostylus_.

V. Subfamily }
Caryostylida. }Polar spines {Both spines
(Five or more } free. { equal, 56. _Caryostylus_.
concentric }
spheres.) }

{Shell a solid spongy sphere
{ without central medullary
{ shell, 57. _Spongolonchis_.
VI. Subfamily {
Spongostylida.{ {One central
(Spherical shell{ { medullary
partially or {In the centre { shell, 58. _Spongostylus_.
wholly of a { of the spongy{
spongy { sphere one or{Two
structure.) { two medullary{ concentric
{ shells. { medullary
{ { shells, 59. _Spongostylidium_.

Subfamily XIPHOSTYLIDA, Haeckel, 1881, Prodromus, pp. 449, 450.

_Definition._--#Stylosphærida# with one simple spherical lattice-shell.

Genus 45. _Xiphosphæra_,[68] Haeckel, 1881, Prodromus, p. 450.

_Definition._--#Stylosphærida# with one single lattice-sphere and two free spines of equal size and form.

The genus _Xiphosphæra_ is the most simple form of all Stylosphærida, and may be regarded as the common ancestral form of this family. On the surface of a simple {123}spherical lattice-shell, enclosing the central capsule, arise two equal, free, radial spines, opposite to each other on the poles of one axis.

Subgenus 1. _Xiphosphærantha_, Haeckel.

_Definition._--Pores of the spherical shell regular, of nearly equal size and form; surface smooth or a little rough, without spines or thorns (other than the two polar spines).

1. _Xiphosphæra planeta_, n. sp.

Pores regular, hexagonal, eight to nine times as broad as the thin bars. Ten to twelve pores on the half equator. Shell very thin walled; surface smooth. Polar spines three-sided pyramidal, about as long as the axis of the sphere, as broad at the base as one pore.

_Dimensions._--Diameter of the sphere 0.12 to 0.13, pores 0.016 to 0.018, bars 0.002; length of the polar spines 0.1 to 0.15, basal thickness 0.02.

_Habitat._--Pacific, central area, surface; Stations 271 to 274, depths 2425 to 2750 fathoms.

2. _Xiphosphæra gæa_, n. sp. (Pl. 14, fig. 5).

Pores regular, circular, with prominent hexagonal crests between them. On the half equator ten to twelve pores, of the same breadth as the crested bars. Shell thin walled; surface smooth. Polar spines three-sided prismatic, about twice as long as the axis of the sphere, twice as broad at the base as one pore.

_Dimensions._--Diameter of the sphere 0.07 to 0.09, pores and bars 0.005; length of the polar spines 0.15 to 0.2, basal thickness 0.01.

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

3. _Xiphosphæra venus_, n. sp. (Pl. 14, fig. 2).

Pores regular, circular, with prominent hexagonal frames. On the half equator fifteen to eighteen pores, of the same breadth as the bars. Shell very thick walled; surface smooth, honeycomb-like. Polar spines conical, smooth, about as long as the axis of the shell, twice as broad at the base as one pore.

_Dimensions._--Diameter of the sphere 0.12 to 0.13, pores and bars 0.005; thickness of the shell wall 0.013; length of the polar spines 0.12 to 0.15, basal breadth 0.01.

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

4. _Xiphosphæra luna_, n. sp.