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.
Dimensions.—Longer axis of the ellipsoid 0.1, shorter axis 0.08; pores 0.004, bars 0.01.
Habitat.—South Pacific, Station 289, surface.
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 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.
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 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.
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 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.
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.
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.
Definition.—Network of the shell irregular, with pores of different size or form.
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.
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.
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.)
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.
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.
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.
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.
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.
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.
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.)
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.
Definition.—Ellipsida with simple ellipsoidal or pear-shaped shell; with a single spine only situated at one pole of the main axis.
The genus Lithapium represents a peculiar modification of Ellipsoxiphus; one of the two opposite polar spines disappears by reduction, and in this way only a single spine remains, at one pole of the main axis. For this reason the shell assumes a characteristic pear-shape, and may easily be confounded with some similar Monocyrtida (Halicapsa).
1. Lithapium pyriforme, n. sp. (Pl. 14, fig. 9).
Proportion of the longer axis to the shorter = 6 : 5. Shell thin walled, with regular, circular pores, four times as broad as the bars; six to eight on the half equator. Surface a little thorny. The single polar spines three-sided pyramidal, as broad at the base as one mesh, about as long as the radius of the shell. (In the specimen figured, there was on the opposite pole a little rudiment of the other lost polar spine; it is missing in other specimens.)
Dimensions.—Major axis of the ellipsoidal shell 0.12, minor axis 0.1; pores 0.02, bars 0.005; length of the single polar spine 0.05, basal thickness 0.02.
Habitat.—Central area of the Pacific, Station 266, depth 2750 fathoms.
2. Lithapium halicapsa, n. sp. (Pl. 14, fig. 8).
Proportion of the longer axis to the shorter = 6 : 5. Shell thin walled, with irregular, lobed meshes, six to eight on the half equator, twice to five times as broad as the bars; each mesh composed of two to five confluent roundish pores. Surface a little thorny. The single polar spine pyramidal, as broad at the base as one mesh, one-third as long as the axis.
Dimensions.—Major axis 0.12, minor axis 0.1; pores 0.01 to 0.02, bars 0.002 to 0.006; length of the single polar spine 0.03, basal thickness 0.02.
Habitat.—Central area of the Pacific, Station 270, depth 2925 fathoms.
3. Lithapium monocyrtis, n. sp. (Pl. 14, fig. 10).
Proportion of the longer axis to the shorter = 7 : 6. Shell thick walled, with irregular, lobed meshes, four to six on the half equator, three to six times as broad as the bars; each mesh composed of three to six confluent roundish pores. Surface quite smooth, without thorns. The single polar spine pyramidal, as broad at the base as the largest mesh, half as long as the radius. (This species is closely allied to the foregoing, but differs in the smooth surface and the larger meshes.)
Dimensions.—Major axis 0.15, minor axis 0.13; pores 0.01 to 0.03, bars 0.003 to 0.01; length of the single spine 0.04, basal thickness 0.03.
Habitat.—Central area of the Pacific, Station 268, depth 2900 fathoms.
Definition.—Ellipsida with simple ellipsoidal shell, the main axis of which is prolonged at the pole into two opposite hollow fenestrated tubes of equal size and similar form.
The genus Pipettella is distinguished from the other Ellipsida by two hollow perforated tubes, which are directed in the longer axis of the ellipsoidal shell and arise from opposite poles of this axis. It may be derived from Cenellipsis by prolongation of both poles of the main axis. As the same peculiar production of two opposite latticed tubuli at the poles of the main axis obtains in nearly all families of Prunoidea (Pipetta, Cannartus, Panarium, Zygartus, &c.), it may possess a peculiar value in this group.
1. Pipettella fusiformis, n. sp.
Shell spindle-shaped, thin walled, the two opposite tubes being conical and not longer than the short transverse axis of the ellipsoidal shell; no sharp demarcation between them. The two axes of the ellipsoid bear the proportion of 3 : 2. Network of the shell and of the tubes equal, delicate, regular, hexagonal, with circular apertures of equal size; fourteen to sixteen on the half equator of the shell. Bars very thin. The shell of this species is similar to that of Cannartiscus amphiconiscus (Pl. 39, fig. 19), but possesses no equatorial stricture and no medullary shell.
Dimensions.—Longer axis of the ellipsoid 0.18, shorter axis 0.12; length of the tubes 0.1, their basal breadth 0.05; pores of the network 0.01, bars 0.001.
Habitat.—Northern Pacific, Station 244, depth 2900 fathoms.