1. Spongellipsis lævis, n. sp.
Shell ellipsoidal, with smooth surface, its spongy wall scarcely one-tenth as thick as the minor axis of the inner cavity. Spongy framework very compact, with small meshes, three to six times as broad as the bars. Proportion of the major axis to the minor = 3 : 2.
Dimensions.—Major axis (or length) of the shell 0.36, minor axis (or breadth) 0.24.
Habitat.—Pacific, central area, Station 265, surface.
2. Spongellipsis aspera, n. sp.
Shell ellipsoidal, with rough surface, its spongy wall nearly half as thick as the minor axis of the inner cavity. Spongy framework very loose, with large meshes, ten to twenty times as broad as the bars. Proportion of the major axis to the minor = 4 : 3.
Dimensions.—Length of the shell 0.24, breadth 0.18.
Habitat.—North Pacific, Station 253, surface.
3. Spongellipsis aplysina, n. sp.
Shell nearly cylindrical, with rough surface, its spongy wall about one-fourth as thick as the minor axis of the internal cavity. Spongy framework loose, with large meshes, four to eight times as broad as the bars. Proportion of both axes = 6 : 1. (Similar to a spongy cylinder of Aplysina.)
Dimensions.—Length of the shell 0.3, breadth 0.05.
Habitat.—North Atlantic, Station 64, surface.
Definition.—Surface of the shell covered with radial spines.
4. Spongellipsis setosa, n. sp.
Shell ellipsoidal, covered with numerous (sixty to eighty) thin, bristle-shaped, radial spines, about half as long as the major axis. Spongy framework loose, with large meshes, ten to twenty times as broad as the bars. Minor axis of the inner cavity twice as long as the thickness of the spongy wall. Proportion of both axes = 5 : 3.
Dimensions.—Length of the shell 0.2, breadth 0.12.
Habitat.—South Atlantic, Station 325, surface.
5. Spongellipsis spinosa, n. sp.
Shell nearly cylindrical, covered with numerous thorns and thirty to forty larger conical radial spines, somewhat longer than the major axis. Spongy framework compact, with small meshes, four to eight times as broad as the bars. Minor axis of the inner cavity about six times as large as the thickness of the spongy wall. Proportion of both axes = 4 : 1.
Dimensions.—Length of the shell 0.24, breadth 0.06.
Habitat.—South Pacific, Station 300, surface.
Definition.—Spongurida with ellipsoidal or cylindrical (sometimes three-jointed) shell, of solid spongy framework, without internal cavity and without latticed medullary shell. Polar spines and outer lattice-mantle absent.
The genus Spongurus was founded by me in 1862 for the common cosmopolitan Spongurus cylindricus, a massive spongy cylinder with radial spines. I enlarge here the conception of the genus, in receiving also ellipsoidal, massive spongy Prunoidea, with or without radial spines. Sometimes the cylindrical shell is more or less distinctly three-jointed, with two annular strictures, as also in the following and nearly allied genus.
Definition.—Spongy framework everywhere of the same structure; surface smooth or rough, but without radial spines.
1. Spongurus stuparius, n. sp.
Shell ellipsoidal, one and a half times as long as broad, with nearly smooth surface. Spongy framework everywhere of equal structure, with small meshes, four to six times as broad as the bars.
Dimensions.—Length of the shell (or major axis) 0.2, breadth of it (or minor axis) 0.14.
Habitat.—South Pacific, Station 295, depth 1500 fathoms.
2. Spongurus stypticus, n. sp.
Shell ellipsoidal, twice as long as broad, with thorny surface. Spongy framework everywhere of equal structure, with large meshes, ten to twenty times as broad as the bars.
Dimensions.—Length of the shell 0.3, breadth 0.15.
Habitat.—Pacific, central area, Station 274, depth 2750 fathoms.
3. Spongurus phalanga, Haeckel.
Spongurus cylindricus, Stöhr, 1880, Palæontogr., vol. xxvi. p. 119, Taf. vii. fig. 3.
Shell nearly cylindrical, five times as long as broad, with thorny surface. Spongy framework compact, everywhere of equal structure, with small meshes, scarcely broader than the bars.
Dimensions.—Length of the shell 0.24, breadth 0.05.
Habitat.—Pacific, central area, Station 268, depth 2600 fathoms; fossil in the Tertiary rocks of Sicily, Stöhr.
Definition.—Spongy framework everywhere of the same structure; surface armed with radial spines.
4. Spongurus asper, Haeckel.
Haliomma asperum, Joh. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 40, Taf. ii. fig. 2.
Haliomma asperum, Haeckel, 1862, Monogr. d. Radiol., p. 431.
Shell ellipsoidal, one and a third times as long as broad, with thorny surface and twenty symmetrically disposed, thin, bristle-shaped, radial spines, about as long as the shell. Spongy framework everywhere of the same structure, very compact, with small meshes, three to four times as broad as the bars.
Dimensions.—Length of the shell 0.11, breadth 0.08.
Habitat.—Mediterranean, Ligurian coast (J. Müller), Portofino (Haeckel).
5. Spongurus cylindricus, Haeckel.
Spongurus cylindricus, Haeckel, 1862, Monogr. d. Radiol., p. 465, Taf. xxvii. fig. 1.
Shell cylindrical, four to five times as long as broad, with nearly smooth surface, and twenty to thirty thin, bristle-shaped, radial spines, about half as long as the shell. Spongy framework everywhere of the same structure, very compact, with small meshes, scarcely broader than the bars.
Dimensions.—Length of the shell 0.2, breadth 0.04 to 0.05.
Habitat.—Cosmopolitan; Mediterranean, Atlantic, and Pacific, surface.
6. Spongurus tricolus, n. sp.
Shell nearly cylindrical, with two slight annular transverse strictures; its middle part is somewhat broader. Surface thorny, with numerous (forty to sixty or more) short, thin, radial spines, not longer than the breadth of the shell. Spongy framework everywhere of the same structure, compact, with small meshes, twice to three times as broad as the bars.
Dimensions.—Length of the shell 0.24, breadth 0.04 to 0.06.
Habitat.—Pacific, central area, Station 272, 2600 fathoms.
Definition.—Spongy framework in the inner part of the shell very compact, in the outer part very loose; surface armed with radial spines.
7. Spongurus radians, n. sp.
Shell ellipsoidal, one and a half times as long as broad, with thorny surface, and eighty to one hundred and twenty (or more) thin, bristle-shaped, radial spines, somewhat longer than the shell. Spongy framework in the inner part very compact, in the outer part very loose, with a gradual transition between the two parts. Meshes in the central part not broader than the bars, in the superficial part ten to twenty times as broad.
Dimensions.—Length of the shell 0.24, breadth 0.16.
Habitat.—Mediterranean, Portofino, near Genoa, Haeckel, surface.
8. Spongurus spongechinus, n. sp.
Shell ellipsoidal, one and a third times as long as broad, with thorny surface, and thirty to forty thick, conical radial spines, about half as long as the shell. Spongy framework in the inner part of the shell compact, in the outer loose, with a gradual transition between the two parts. Meshes in the central part smaller than the bars, in the superficial part four to eight times as broad.
Dimensions.—Length of the shell 0.18, breadth 0.14.
Habitat.—North Atlantic, Station 353, surface.
Definition.—Spongurida with ellipsoidal or cylindrical (sometimes three-jointed) shell of solid spongy framework, without internal cavity and without latticed medullary shell. Polar spines absent. An outer lattice-mantle is connected with the spongy shell by radial beams.
The genus Spongocore contains some widely distributed Spongurida, which are distinguished from the nearly related Spongurus by the development of a peculiar veil or mantle of delicate lattice-work, which envelops either the whole shell or only the middle part of it, and is connected with it by numerous radial beams. The distance of the simple fine lattice-lamella from the spongy shell is everywhere the same. Often the cylindrical shell is three-jointed, with two annular strictures, as also in the foregoing Spongurus. It is derived from the latter by development of the veil connecting the points of the radial spines.
Definition.—Shell without distinct annular strictures, not evidently three-jointed.
1. Spongocore velata, n. sp.
Shell ellipsoidal, one and a half times as long as broad, without annular strictures. Spongy framework loose, with rather large meshes, four to six times as broad as the bars. The whole spongy shell enveloped by a delicate veil with smooth surface, connected with it by numerous thin radial beams. Breadth of the spongy ellipsoid (or minor axis) six times as large as its distance from the veil.
Dimensions.—Length of the whole shell (with veil) 0.3, breadth 0.2; distance of the veil from the spongy ellipsoid 0.035.
Habitat.—South Atlantic, Station 325, surface.
2. Spongocore diplocylindrica, n. sp.
Shell cylindrical, three times as long as broad, without annular strictures. Spongy framework compact, with small meshes, twice to three times as broad as the bars. The whole surface of the spongy cylinder, with exception of both rounded polar faces, enveloped by a delicate cylindrical veil with smooth surface, connected with it by numerous radial beams. Diameter of the spongy cylinder twice as large as its distance from the veil.
Dimensions.—Length of the shell 0.3, breadth (with veil) 0.1; distance of the veil 0.025.
Habitat.—South Pacific, Station 302, surface.
Definition.—Shell distinctly three-jointed, with two transverse annular strictures.
3. Spongocore chrysalis, n. sp.
Spongy shell cylindrical, without the veil six times as long as broad, three-jointed, with two annular strictures; all three joints of the same length. The whole spongy shell enveloped by a thin veil with thorny surface, connected with it by numerous radial beams. Breadth of the spongy cylinder three times as large as its distance from the veil.
Dimensions.—Length of the shell (with veil) 0.4, breadth 0.1; distance of the veil from the spongy shell 0.02.
Habitat.—South Atlantic (off Patagonia), Station 318, surface.
4. Spongocore cincta, n. sp.
Spongy shell cylindrical, without the veil four times as long as broad, three-jointed, with two annular strictures; all three joints of the same length. Only the middle joint enveloped by a thin veil with smooth surface, connected with it by radial beams. Both terminal joints with long, bristle-shaped, radial spines. Breadth of the spongy cylinder twice as large as its distance from the veil.
Dimensions.—Length of the shell 0.24, breadth (with veil) 0.12; distance of the veil 0.03.
Habitat.—Indian Ocean, Madagascar, Rabbe, surface.
5. Spongocore pupula, n. sp.
Spongy shell cylindrical, without the veil six times as long as broad, three-jointed, with two annular strictures; the middle joint half as long as either terminal joint. Only the middle joint enveloped by a thin veil with spiny surface, connected with it by twenty to thirty radial beams, which are prolonged on the outside into short radial spines. Breadth of the spongy cylinder about equal to its distance from the veil.
Dimensions.—Length of the shell 0.2, breadth (with veil) 0.1; distance of the veil 0.033.
Habitat.—North Pacific, Station 244, surface.
6. Spongocore puella, n. sp. (Pl. 48, fig. 6).
Spongy shell cylindrical, without the veil five times as long as broad, three-jointed, with two annular strictures; the middle joint twice as long as either terminal joint. Only the middle joint enveloped by a thin veil with delicate lattice-work and smooth surface; both terminal joints armed with numerous thin, bristle-shaped, radial spines. Breadth of the spongy cylinder twice as large as the distance from the veil.
Dimensions.—Length of the shell 0.25 to 0.3, breadth (with veil) 0.1 to 0.12; distance of the veil 0.028 to 0.032.
Habitat.—South Pacific, Stations 295 to 304, surface.
Definition.—Spongurida with ellipsoidal or cylindrical shell of solid spongy framework, without internal cavity and without latticed medullary shell. On the poles of the axis occur two opposite strong spines.
The genus Spongoprunum differs from the most nearly allied Spongurus by the possession of two strong solid spines, lying in the axis of the ellipsoidal or cylindrical massive spongy shell, on its two opposite poles. Spongoprunum bears therefore the same relation to Spongurus that Ellipsoxiphus does to Cenellipsis.
1. Spongoprunum amphilonche, n. sp. (Pl. 48, fig. 7).
Shell ellipsoidal, two and a third times as long as broad, with nearly smooth surface. Spongy framework very compact, in the whole solid shell of the same structure, with very small meshes, scarcely broader than the bars. Two polar spines conical, very strong, about half as long as the main axis of the shell and three times as long as broad.
Dimensions.—Length of the shell (without spines) 0.2, breadth 0.08.
Habitat.—Central Pacific, Station 265, depth 2900 fathoms; fossil in the rocks of Barbados.
2. Spongoprunum atractus, n. sp.
Shell spindle-shaped, twice as long as broad, with thorny surface. Spongy framework loose, in the whole shell of the same structure, with large meshes, eight to twelve times as broad as the bars. Two polar spines angular, pyramidal, very strong, about one-third as long as the shell, and twice as long as broad.
Dimensions.—Length of the shell 0.2, breadth 0.11.
Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.
3. Spongoprunum amphicylindrus, n. sp.
Shell nearly cylindrical, four times as long as broad, with rough surface. Spongy framework compact, in the whole shell of equal structure, with small meshes, twice to three times as broad as the bars. Two polar spines cylindrical, very large, longer than the shell, and about one-fourth as thick as its diameter.
Dimensions.—Length of the shell 0.2, breadth 0.05.
Habitat.—South Atlantic, Station 333, surface.
Definition.—Spongurida with latticed medullary shell, enclosed by a spongy cortical shell.
Definition.—Spongurida with spongy ellipsoidal cortical shell, enclosing a simple, spherical or ellipsoidal, latticed medullary shell. Polar spines absent.
The genus Spongodruppa opens the series of Spongodruppida, or of those Spongurida in which the ellipsoidal spongy cortical shell encloses a simple or double, latticed, medullary shell. In Spongodruppa, the simplest and probably the ancestral form of this subfamily, the medullary shell is simple and the polar spines absent. It may be derived from Druppula by a spongy thickening of the simple latticed cortical shell.
Definition.—Surface of the shell smooth or rough, without radial spines.
1. Spongodruppa terebintha, n. sp.
Cortical shell one and a third times as long as broad, with smooth surface, three times as broad as the spherical medullary shell. Spongy framework very compact, with small meshes of the same breadth as the bars. Thickness of the spongy wall equal to the radius of the medullary shell.
Dimensions.—Length of the cortical shell (or major axis of the ellipsoid) 0.16, breadth (or minor axis) 0.12; thickness of its wall 0.02; medullary shell 0.04.
Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.
2. Spongodruppa pistacia, n. sp.
Cortical shell one and a half times as long as broad, with thorny surface, nearly five times as broad as the spherical medullary shell. Spongy framework compact, its thickness equal to the diameter of the medullary shell.
Dimensions.—Length of the cortical shell 0.2, breadth 0.14; thickness of its wall 0.03; medullary shell 0.03.
Habitat.—Fossil in the rocks of Barbados.
3. Spongodruppa lentisca, n. sp.
Cortical shell twice as long as broad, with rough surface, four times as large as the ellipsoidal medullary shell. Spongy framework loose, with large meshes, its thickness equal to the length of the medullary shell.
Dimensions.—Length of the cortical shell 0.25, breadth 0.13; thickness of its wall 0.06; length of the medullary shell 0.06, breadth 0.04.
Habitat.—Pacific, central area, Station 266, surface.
Definition.—Surface of the shell armed with radial spines.
4. Spongodruppa frangula, n. sp.
Cortical shell one and a third times as long as broad, three times as broad as the spherical medullary shell. Spongy framework loose, with large meshes, its thickness half as large as the diameter of the medullary shell. Surface covered with numerous (forty to fifty) thin, bristle-shaped, radial spines, about as long as the cortical shell.
Dimensions.—Length of the cortical shell 0.24, breadth 0.18; thickness of its wall 0.035; diameter of the medullary shell 0.06.
Habitat.—North Pacific, Station 244, depth 2900 fathoms.
5. Spongodruppa elliptica, Haeckel.
Acanthosphæra elliptica, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 285, Taf. vii. fig. 4.
Cortical shell nearly twice as long as broad, four times as broad as the ellipsoidal medullary shell. Spongy framework compact, with small meshes. Surface covered with very numerous short radial spines, about as long as the medullary shell.
Dimensions.—Length of the cortical shell 0.2, breadth 0.11; length of the medullary shell 0.04, breadth 0.03.
Habitat.—Philippine Sea, Ehrenberg, Station 206, depth 2100 fathoms.
6. Spongodruppa polyacantha, Haeckel.
Haliomma polyacanthum, J. Müller, 1858, Abhandl., p. 36, Taf. i. figs. 10, 11.
Haliomma polyacanthum, Haeckel, 1862, Monogr. d. Radiol., p. 430.
Cortical shell one and a third times as long as broad, twice as broad as the ellipsoidal medullary shell. Spongy framework loose on the surface, with large regular meshes. Surface covered with fifteen to twenty thick, conical spines, about as long as the radius of the shell.
Dimensions.—Length of the cortical shell 0.12, of the medullary shell 0.09; diameter of the medullary shell 0.05 to 0.06.
Habitat.—Mediterranean (south coast of France); Atlantic (Canary Islands), Station 354, surface.
Definition.—Spongurida with spongy ellipsoidal cortical shell, enclosing a simple, spherical or ellipsoidal, latticed medullary shell. On the poles of the axis occur two opposite strong spines.
The genus Spongatractus differs from Spongodruppa by development of two strong spines in the axis of the shell, on its two opposite poles; therefore it bears the same relation to the latter that Lithatractus does to Druppula, and can be derived from Lithatractus by a spongy thickening of the cortical shell.
1. Spongatractus pachystylus, Haeckel.
Spongosphæra pachystyla, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xxvi. fig. 3.
Cortical shell one and a half times as long as broad, with rough surface. Spongy framework compact, with small meshes, about as thick as the spherical medullary shell. Polar spines very stout, conical, slightly sulcated, about as long as the breadth of the cortical shell, as broad at the base as the medullary shell.
Dimensions.—Length of the cortical shell 0.2, breadth 0.13; thickness of the spongy wall 0.045; diameter of the medullary shell 0.04.
Habitat.—Fossil in the rocks of Barbados, Ehrenberg; living in the Equatorial Atlantic, Station 348, depth (2450) fathoms.
2. Spongatractus fusiformis, n. sp.
Cortical shell one and a third times as long as broad, with nearly smooth surface. Spongy framework very compact, with very small meshes, about as thick as the radius of the spherical medullary shell. Polar spines very strong, three-sided pyramidal, about as long as the breadth of the cortical shell, as broad at the base as the medullary shell.
Dimensions.—Length of the cortical shell 0.16 to 0.18, breadth 0.12 to 0.14; thickness of the spongy wall 0.02; diameter of the medullary shell 0.04.
Habitat.—Pacific, central area, Station 268, depth 2900 fathoms.
3. Spongatractus streptacanthus, n. sp.
Cortical shell twice as long as broad, with thorny surface. Spongy framework loose, with large meshes, about as thick as the ellipsoidal medullary shell. Polar spines very long, three-sided prismatic, with three spirally contorted edges, much longer than the cortical shell, half as broad as the medullary shell.
Dimensions.—Length of the cortical shell 0.25, breadth 0.13; thickness of the spongy wall 0.03; diameter of the medullary shell 0.03 to 0.04.
Habitat.—North Atlantic, off Canary Islands, Haeckel.
Definition.—Spongurida with spongy ellipsoidal cortical shell, enclosing a double, spherical or ellipsoidal, latticed medullary shell. Polar spines absent.
The genus Spongoliva differs from the nearest Spongodruppa by duplication of the medullary shell; it bears therefore the same relation to this that Prunulum does to Druppula, and can be regarded as a Prunulum, in which the simple latticed cortical shell is replaced by a spongy framework.
Definition.—Surface of the shell smooth or rough, without radial spines.
1. Spongoliva cerasina, n. sp.
Cortical shell one and a fourth times as long as broad, with smooth surface, four times as broad as the outer spherical medullary shell. Spongy framework very compact, with very small meshes, its thickness equal to the diameter of the outer medullary shell.
Dimensions.—Length of the cortical shell 0.2, breadth 0.16; thickness of its wall 0.04; diameter of the outer medullary shell 0.04, of the inner 0.014.
Habitat.—Fossil in the rocks of Barbados.
2. Spongoliva prunulina, n. sp.
Cortical shell one and a third times as long as broad, with smooth surface, three times as large as the outer ellipsoidal medullary shell. Spongy framework very compact, with small meshes, its thickness equal to the diameter of the inner medullary shell.
Dimensions.—Length of the cortical shell 0.24, breadth 0.18; thickness of its wall 0.03; size of the outer medullary shell 0.08 to 0.06, of the inner 0.03.
Habitat.—Pacific, central area, Station 265, depth 2900 fathoms.
3. Spongoliva persicina, n. sp.
Cortical shell one and a half times as long as broad, with rough surface, five to six times as large as the ellipsoidal outer medullary shell. Spongy framework loose, with large meshes, its thickness about equal to the outer medullary shell.
Dimensions.—Length of the cortical shell 0.26, breadth 0.18; thickness of its wall 0.04; size of the outer medullary shell 0.045 to 0.035, of the inner 0.015.
Habitat.—Equatorial Atlantic, Station 348, depth (2450) fathoms.
4. Spongoliva amygdalina, n. sp.
Cortical shell twice as long as broad, with thorny surface, ten times as long as the small spherical outer medullary shell. Spongy framework loose, with large meshes, its thickness one and a half times as large as the outer medullary shell.
Dimensions.—Length of the cortical shell 0.3, breadth 0.16; thickness of its wall 0.045; size of the outer medullary shell 0.03, of the inner 0.015.
Habitat.—Fossil in the Tertiary rocks of Sicily (Caltanisetta).
Definition.—Surface of the shell armed with radial spines.
5. Spongoliva opuntina, n. sp.
Cortical shell one and a third times as long as broad, armed with numerous thin, bristle-shaped, radial spines, nearly as long as the shell. Spongy framework loose, with large meshes, its thickness nearly equal to the diameter of the outer spherical medullary shell.
Dimensions.—Length of the cortical shell 0.18, breadth 0.14; thickness of its wall 0.035; diameter of the outer medullary shell 0.04, of the inner 0.02.
Habitat.—South Atlantic, Station 325, surface.
6. Spongoliva daturina, n. sp.
Cortical shell one and a half times as long as broad, armed with numerous, thick and short, conical radial spines, about as long as the outer medullary shell. Spongy framework compact, with small meshes, its thickness equal to half the length of the outer ellipsoidal medullary shell.
Dimensions.—Length of the cortical shell 0.24, breadth 0.16; thickness of its wall 0.025; diameter of the outer medullary shell 0.045 to 0.035, of the inner 0.025.
Habitat.—Pacific, central area, Station 272, surface.
Definition.—Spongurida with spongy ellipsoidal cortical shell, enclosing a double, spherical or ellipsoidal, latticed medullary shell. On the poles of the axis occur two opposite strong spines.
The genus Spongoxiphus differs from Spongoliva by the development of two strong spines in the axis of the shell, on its two opposite poles. From the similar Spongatractus it differs in the duplication of the medullary shell. It may also be regarded as a Stylatractus, in which the simple latticed cortical shell is replaced by an irregular spongy framework.
1. Spongoxiphus sphærococcus, n. sp.
Cortical shell one and a half times as long as broad, with thorny surface. Spongy framework compact, with small meshes, its thickness equal to the radius of the outer medullary shell. Both medullary shells spherical, the outer three times as broad as the inner. Polar spines very stout, conical, slightly sulcated, about half as long as the cortical shell, as broad at the base as the outer medullary shell. (Differs from Spongatractus pachystylus almost only in the double medullary shell.)
Dimensions.—Length of the cortical shell 0.18, breadth 0.12; thickness of the spongy wall 0.025; diameter of the outer medullary shell 0.05, of the inner 0.016.
Habitat.—Fossil in the rocks of Barbados (Haeckel); also living in the Pacific, central area, Station 265, depth 2900 fathoms.
2. Spongoxiphus prunococcus, n. sp. (Pl. 17, figs. 12, 13).
Spongostylus prunococcus, Haeckel, 1881, Prodromus, p. 455, et Atlas, pl. xvii. figs. 12, 13.
Cortical shell one and a third times as long as broad, with smooth surface. Spongy framework very compact, with very small meshes, its thickness about equals the breadth of the outer medullary shell. Both medullary shells ellipsoidal, the outer three times as large as the inner. Polar spines very stout, three-sided pyramidal, about half as long as the cortical shell, on the base about as broad as the outer medullary shell. (Differs from the preceding in the ellipsoidal form of both medullary shells, and in the finer structure of the spongy framework.)
Dimensions.—Length of the cortical shell 0.18 to 0.2, breadth 0.14 to 0.16; thickness of the spongy wall 0.035 to 0.04; length of the outer medullary shell 0.04 to 0.06, breadth 0.03 to 0.04.
Habitat.—Pacific, central area, Stations 265 to 268, depths 2700 to 2900 fathoms.
Artiscida, Haeckel, 1881, Prodromus, p. 462.
Definition.—Prunoidea with an ellipsoidal twin-shell divided by an equatorial stricture into two communicating hemiellipsoidal or hemispherical chambers, without enclosed medullary shell. Central capsule ellipsoidal, with or without equatorial stricture.
The family Artiscida has a simple fenestrated outer shell, like that of the Ellipsida, but differs from these in the presence of an equatorial constriction, by which it assumes a characteristic twin form, somewhat similar to a violin (Pl. 39, figs. 9, 10). From the Cyphinida, which have the same form of the cortical shell, the Artiscida differ in the absence of the medullary shell. It is possible that the Artiscida are descended from the Cyphinida (by loss of the medullary shell), but it is more probable that they arise from the Ellipsida by an annular constriction in the equatorial plane (perhaps the formation of the shell originally took place while the central capsule was undergoing division). Both halves of the twin shell are always of the same size and form. Its outer surface is either smooth or covered with radial spines (Artiscus, Pl. 39, fig. 9). Sometimes on the opposite poles of the main axis are developed solid spines (Stylartus, Pl. 48, fig. 5) or hollow fenestrated tubes (Cannartus, Pl. 39, fig. 10).
The Central Capsule is either simply ellipsoidal, or has also an equatorial constriction, which divides it into two equal halves. It is constantly smaller than the surrounding shell, and separated from its inner surface by a thicker or thinner jelly-mantle, the calymma.
| On the poles of the main axis neither solid spines nor hollow tubes, | 152. Artiscus. |
| On the poles of the main axis two solid spines (or bunches of spines), | 153. Stylartus. |
| On the poles of the main axis two hollow fenestrated tubes, | 154. Cannartus. |
| On the poles of the main axis neither solid spines nor hollow tubes, | ||
| 152. Artiscus. | ||
| On the poles of the main axis two solid spines (or bunches of spines), | ||
| 153. Stylartus. | ||
| On the poles of the main axis two hollow fenestrated tubes, | ||
| 154. Cannartus. | ||
Definition.—Artiscida without peculiar polar appendages (without strong solid spines or hollow fenestrated tubes on the poles of the main axis).
The genus Artiscus represents the most simple and primitive form of the Artiscida, and may therefore be regarded as the ancestral form of this subfamily. It resembles an ordinary double loaf, composed of two equal, nearly ellipsoidal fenestrated shells separated by the stricture in the equatorial plane. Artiscus can be derived from Cenellipsis simply by this equatorial constriction. But it can also be derived from Cyphanta by loss of the medullary shell.
Definition.—Surface of the shell smooth or rough, without radial rods or spines.
1. Artiscus paniscus, n. sp.
Pores of the shell regular, hexagonal, four times as broad as the bars; ten to twelve pores on the half meridian, eight to nine on the half equator. Surface smooth. (The network of this species is quite the same as that of the proximal cameræ of Panartus diploconus, Pl. 40, fig. 1.)
Dimensions.—Main axis of the shell 0.12, equatorial axis 0.07; meshes 0.013, bars 0.003.
Habitat.—Pacific, central area, Station 271, depth 2425.
2. Artiscus facetus, n. sp.
Pores of the shell regular, circular, with prominent hexagonal frame, twice as broad as the bars; twenty-two to twenty-four pores on the half meridian, fourteen to fifteen on the half equator. Surface a little thorny. (The shell of this species exhibits nearly the same formation as that of Cyphonium virgineum, Pl. 39, fig. 12, but without enclosed medullary shells.)
Dimensions.—Main axis of the shell 0.15, equatorial axis 0.09; meshes 0.01, bars 0.005.
Habitat.—Pacific, central area, Station 266, depth 2750 fathoms.
3. Artiscus paniculus, n. sp.
Pores of the shell regular, circular, without hexagonal frame, as broad as the bars; fourteen to sixteen pores on the half meridian, ten to eleven on the half equator. Surface quite smooth.
Dimensions.—Main axis of the shell 0.13, equatorial axis 0.06; meshes 0.01, bars 0.01.
Habitat.—Fossil in the Tertiary rocks of Barbados (Haeckel).
4. Artiscus panarius, n. sp.
Pores of the shell irregular, roundish, twice to four times as broad as the bars; sixteen to eighteen pores on the half meridian, twelve to thirteen on the half equator. Surface smooth.
Dimensions.—Main axis of the shell 0.11, equatorial axis 0.06; meshes 0.005 to 0.02, bars 0.001 to 0.004.
Habitat.—Western Tropical Pacific, Station 224, depth 1850 fathoms.
Definition.—Surface of the shell covered with radial rods or spines.
5. Artiscus elegans, n. sp.
Pores of the shell regular, circular, with hexagonal frames, twice as broad as the bars; fourteen pores on the half meridian, eight to nine on the half equator. From every corner of the hexagonal frames (between every three pores) starts a thin, three-sided pyramidal spine, twice as large as a pore.
Dimensions.—Main axis 0.13, equatorial axis 0.08; meshes 0.007, bars 0.004; spines 0.015 long.
Habitat.—South Atlantic, Station 332, depth 2200 fathoms.
6. Artiscus nodosus, n. sp. (Pl. 39, fig. 9).
Pores of the shell subregular, circular, without hexagonal frame, three times as broad as the bars; sixteen to eighteen on the half meridian, ten to twelve on the half equator. Irregularly scattered on the whole surface a variable number (twenty-five to thirty in all) of stout short radial spines or rather blunt rods; the length and thickness of these is the same, and equals the size of two to three meshes; its form resembles a truncated six-sided pyramid.
Dimensions.—Main axis 0.11, equatorial axis 0.08; meshes 0.01, bars 0.003; length and thickness of the radial sticks 0.02.
Habitat.—Pacific, central area, Station 272, depth 2600 fathoms.
7. Artiscus hystrix, n. sp.
Pores of the shell irregular, roundish, of very unequal size and dissimilar form, twice to eight times as broad as the bars; ten to fifteen on the half meridian, seven to nine on the half equator. Irregularly scattered on the whole surface a large number of thin conical spines, about as large as the meshes, partly directed radially, partly obliquely. (The shell of this species resembles very much that of Cyphonium ceratospyris (p. 366) = Didymocyrtis ceratospyris, Monogr. d. Radiol., 1862, Taf. xxii. fig. 14, but is without the enclosed inner shells.)