Dimensions.—Major axis 0.12, minor 0.08; pores 0.06 to 0.012, bars 0.003; main axes of the medullary shells 0.05 and 0.025.
Habitat.—Indian Ocean, between Socotra and Ceylon, surface, Haeckel.
8. Prunulum fenestratum, Haeckel.
Actinomma fenestratum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 94, Taf. iii. fig. 2.
Cortical shell thick walled, rough, with irregular, roundish pores, once to three times as broad as the bars; twelve to fourteen on the half equator. Proportion of the two axes = 9 : 8. Both medullary shells ellipsoidal. (The pores in Stöhr's description are by mistake called "regular"; in the figure they are very irregular, as also in the fossil specimens observed by myself. Between the cortical pores arise very short irregular thorns.)
Dimensions.—Major axis 0.12 to 0.15, minor 0.1 to 0.12; pores 0.003 to 0.01, bars 0.003; main axis of the outer medullary shell 0.07 to 0.09, of the inner 0.03 to 0.04.
Habitat.—Fossil in the Tertiary rocks of Sicily; Grotte, Stöhr, Caltanisetta, Haeckel.
9. Prunulum pyrenium, n. sp.
Cortical shell very thick walled, smooth, with large irregular, roundish pores, three to four times as broad as the bars; six to eight on the half equator. The bottom of each funnel-like pore is closed by a thin siliceous membrane, perforated by three to five irregular roundish pores. Proportion of the two axes = 4 : 3. Both medullary shells ellipsoidal. (Closely resembles Stylatractus sethoporus, Pl. 17, figs. 2, 3, but is devoid of the polar spines.)
Dimensions.—Major axis 0.16, minor 0.12; pores 0.015 to 0.02, bars 0.005; porules 0.01; main axes of the medullary shells 0.07 and 0.03.
Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.
Definition.—Druppulida with simple ellipsoidal cortical shell and double medullary shell, with numerous radial spines, but without polar tubes.
The genus Prunocarpus differs from Prunulum only in the radial spines of the cortical shell, and exhibits therefore the same relation to it that Druppocarpus bears to Druppula. While in the latter the medullary shell is simple, in the former it is double.
Definition.—Network of the cortical shell regular, with meshes of equal size and similar form.
1. Prunocarpus datura, n. sp.
Cortical shell thick walled, with regular, circular pores, twice as broad as the bars; ten to twelve on the half equator. Between every three meshes arises a short conical spine, twice to three times as long as one pore. Both medullary shells spherical. (Differs mainly from Ellipsidium datura and from Druppocarpus castanea in the double medullary shell. The outer network resembles Haliomma castanea, figured 1862 in my Monograph, Taf. xxiv. fig. 4.)
Dimensions.—Major axis of the ellipsoid 0.16, minor 0.12; pores 0.012, bars 0.006; length of the radial spines 0.03; diameter of the medullary shells 0.06 and 0.04.
Habitat.—North Atlantic, Færöe Channel, John Murray, surface.
2. Prunocarpus sparganium, n. sp.
Cortical shell thick walled, with very small, numerous, regular, circular pores, of the same size as the bars; forty to fifty on the half equator. Between them over the entire surface occur small conical spines. Irregularly scattered over the surface ten to twenty larger conical spines, three to six times as thick at the base as one pore, one-fourth to one-half as long as the main axis. Both medullary shells ellipsoidal.
Dimensions.—Major axis of the cortical shell 0.16, of the outer medullary shell 0.11, of the inner 0.06; equatorial axis of the first shell 0.12, of the second 0.08, of the third 0.04; pores and bars on an average 0.005; length of the spines 0.05 to 0.1, basal breadth 0.02 to 0.03.
Habitat.—Fossil in the Barbados deposits (Haeckel).
Definition.—Network of the cortical shell irregular, with meshes of different size or form.
3. Prunocarpus artocarpium, n. sp. (Pl. 39, fig. 5).
Cortical shell thin walled with irregular, roundish pores of very different sizes, twice to nine times as broad as the thin bars; ten to fifteen on the half equator. Between them arise numerous bristle-shaped, radial spines, with conical base, on an average one-fourth to two-thirds as long as the equatorial axis. The outer medullary shell, with irregular, roundish pores, presents a transverse ellipsoid, its main axis lying in the equatorial axis of the cortical shell, whilst its equatorial axis corresponds to the main axis of the latter. Inner medullary shell very small, spherical, with very small pores.
Dimensions.—Major axis of the cortical shell 0.14, of the outer medullary shell 0.05; minor axis of the former 0.1, of the latter 0.035; diameter of the inner medullary shell 0.014; pores of the cortical shell 0.005 to 0.02, bars 0.002; length of the radial spines 0.02 to 0.06.
Habitat.—Indian Ocean, surface; Ceylon, Belligemma, Haeckel.
4. Prunocarpus melocactus, n. sp.
Cortical shell thick walled, with irregular, roundish pores, twice to five times as broad as the bars; eighteen to twenty-four on the half equator. Between them arise over the entire surface small conical thorns, not longer than the largest pores. Irregularly scattered over the surface twenty to thirty strong, conical, radial spines, about half as long as the main axis, as broad at the base as a large pore. Both medullary shells ellipsoidal, their main axis identical with that of the cortical shell.
Dimensions.—Major axis of the outer shell 0.18, of the middle 0.09, of the inner 0.05; minor axis of the first 0.14, of the second 0.07, of the third 0.04; pores of the cortical shell 0.006 to 0.02, bars 0.004; length of the spines 0.1, basal breadth 0.01.
Habitat.—Pacific, central area, Station 268, depth 2900 fathoms; also fossil in the Tertiary rocks of Sicily; Caltanisetta, Haeckel.
Definition.—Druppulida with four or more concentric shells (two medullary and two or more cortical shells), without spines or polar tubes.
The genus Cromyodruppa is characterised by the multiplication of the concentric fenestrated shell, which is composed of two medullary shells (enclosed in the central capsule) and two or more cortical shells (outside it). The former may be either spherical or ellipsoidal. The latter are always ellipsoidal, and in this it differs from Cromyosphæra. Probably Cromyodruppa has arisen from Prunulum by secondary apposition of more cortical envelopes.
Definition.—Shell composed of four concentric shells, two medullary and two cortical.
1. Cromyodruppa cepa, n. sp.
Shell composed of two ellipsoidal, cortical, and two spherical medullary shells. Proportion of the main axes of the four shells = 1 : 2 : 4 : 5. Network of all four shells nearly of the same form, subregular, with circular pores of almost equal size in every shell. The absolute size of the pores increases from the innermost to the outermost shell, but the breadth of the bars does not increase in a similar degree. The bars of the outermost shell are only twice as broad as those of the innermost; but the pores are three to four times larger. Surface of all four shells smooth. (The shell greatly resembles that of Cromyatractus tetraphractus, Pl. 15, fig. 2, but is devoid of polar spines; it differs also in the spherical form of both medullary shells and their relative size.)
Dimensions.—Main axes of the four shells—(A) innermost 0.035, (B) second 0.08, (C) third 0.15, (D) outermost 0.2; their equatorial axes—(A) 0.03, (B) 0.08, (C) 0.12, (D) 0.16; pores 0.004 to 0.016, bars 0.002 to 0.004.
Habitat.—Western Tropical Pacific, Station 198, depth 2150 fathoms.
Definition.—Shell composed of five or more concentric shells (two medullary and three or more cortical).
2. Cromyodruppa mango, n. sp.
Shell composed of six ellipsoidal, concentric shells, two medullary and four cortical. Proportion of their main axes = 2 : 3 : 8 : 11 : 14 : 18. Network of the two medullary shells and of the innermost cortical shell subregular, with subcircular pores, about the same breadth as the bars. Network of the three outer cortical shells more lax, with larger, irregular, roundish pores, twice to six times as broad as the bars. The size of the pores and bars increases gradually from the innermost to the outermost shell. Surface smooth.
Dimensions.—Main axis of the six shells—(A) innermost 0.04, (B) 0.06, (C) 0.16, (D) 0.22, (E) 0.28, (F) 0.35; their equatorial axes—(A) innermost 0.03, (B) 0.05, (C) 0.12, (D) 0.16, (E) 0.2, (F) 0.25; pores 0.003 to 0.02, bars 0.003 to 0.005.
Habitat.—Indian Ocean, surface; Matura, Ceylon, Haeckel.
Definition.—Druppulida with four or more concentric shells (two medullary and two or more cortical shells), with numerous radial spines, but without polar tubes.
The genus Cromyocarpus differs from Cromyodruppa only in the development of numerous large radial spines which start from the outer surface of the shell. It exhibits therefore the same relation to the latter that Prunocarpus bears to Prunulum, or Druppocarpus to Druppula. It differs from both in the multiplication of the cortical shell.
1. Cromyocarpus quadrifarius, n. sp.
Shell composed of four concentric shells, two ellipsoidal cortical shells, and two spherical medullary shells. Proportion of their main axes = 10 : 8 : 3 : 2. Pores of the two cortical shells irregular, roundish, twice to four times as broad as the bars. Pores of the two medullary shells subregular, circular, about the same size as the bars. Outer surface covered with numerous conical radial spines, about half as long as the main axis, half as broad at the base as the innermost shell.
Dimensions.—Major axis of the outer cortical shell 0.2, of the inner 0.15; equatorial axis of the former 0.16, of the latter 0.12; diameter of the outer medullary shell 0.06, of the inner 0.04; pores of the cortical shells 0.01 to 0.02, of the medullary shells 0.004 to 0.008, bars 0.003 to 0.006; length of the radial spines 0.1, basal breadth 0.02.
Habitat.—Indian Antarctic Ocean, Station 157, depth 1950 fathoms.
Definition.—Druppulida with simple ellipsoidal cortical shell and simple medullary shell, with two large opposite polar spines in the main axis of equal size and similar form.
The genus Lithatractus, rich in common and widely distributed species, begins the series of those Druppulida which are characterised by peculiar polar spines at both poles of the main axis. It repeats the formation of Stylosphæra and Ellipsostylus, and differs from the former in the ellipsoidal form of the cortical shell, from the latter in the possession of a medullary shell. Formerly all these forms were united in the one genus Stylosphæra (see above, p. 121).
Definition.—Network of the outer shell regular or subregular, with meshes of nearly equal size and similar form; surface smooth, without thorns or papillæ.
1. Lithatractus hexagonalis, n. sp.
Outer shell thin walled, smooth, without thorns or papillæ, with regular delicate network; the meshes hexagonal, three to four times as broad as the thin bars; ten to twelve on the half equator. Proportion of the major axis of the ellipsoid to the minor = 4 : 3. Minor axis three times as large as that of the inner spherical shell; pores of the latter, small, circular. Two spines three-sided pyramidal, as long as the radius of the outer shell, each as broad at its base as one mesh.
Dimensions.—Longer axis of the ellipsoidal cortical shell 0.16, shorter axis 0.12; pores 0.011, bars 0.003; diameter of the spherical medullary shell 0.04; length of the polar spines 0.07; basal breadth 0.01.
Habitat.—North Pacific, Station 253, depth 3125 fathoms.
2. Lithatractus fragilis, n. sp. (Pl. 16, fig. 3).
Stylosphæra fragilis, Haeckel, 1881, Prodromus et Atlas, pl. xvi. fig. 3.
Outer shell thin walled, smooth, without thorns or papillæ, with regular network; the meshes circular, of equal size, eight to ten times as broad as the thin bars; six to eight on the half equator. Proportion of the major axis of the ellipsoid to the minor = 5 : 4. Minor axis once and one-third as broad as that of the ellipsoidal inner shell, the pores of which are also circular, but of half the size. Two spines strong, three-sided pyramidal, acute, as broad as a large mesh, as long as the equatorial axis. The stout inner prolongations of these form the only connection between the two shells.
Dimensions.—Longer axis of the ellipsoidal cortical shell 0.12, shorter axis 0.1; pores 0.02, bars 0.002; longer axes of the ellipsoidal medullary shell 0.09, shorter axis 0.07; pores 0.01, bars 0.002; length of the polar spines 0.1, basal breadth 0.002.
Habitat.—Central area of the Pacific, Station 272, depth 2600 fathoms.
3. Lithatractus leptostylus, n. sp.
Outer shell thin walled, smooth, with regular, circular pores of equal size, three to four times as broad as the thin bars; ten to twelve on the half equator. Proportion of the major axis to the minor = 7 : 6. Minor axis three times as large as that of the inner spherical shell; pores of the latter half as large. Polar spines cylindrical, blunt, longer than the major axis, scarcely half as broad as one larger pore.
Dimensions.—Longer axis of the cortical shell 0.14, shorter axis 0.12; pores 0.015 to 0.02, bars 0.004; diameter of the medullary shell 0.04; length of the polar spines 0.15 to 0.2, its thickness 0.01.
Habitat.—Central area of the Pacific, Stations 270 to 272, depth 2425 to 2925 fathoms.
4. Lithatractus pachystylus, n. sp.
Outer shell thick walled, smooth, with regular, circular pores of equal size; twelve to fifteen on the half equator. Each pore is deep, funnel-shaped, its outer aperture double the size of the inner, its breadth about three times that of the high bars. Proportion of the major axis to the minor = 6 : 5. Major axis double as long as the diameter of the spherical medullary shell. Polar spines very thick and short, tetrahedral, one-fourth as long and broad as the major axis.
Dimensions.—Longer axis of the cortical shell 0.17, shorter axis 0.14; pores 0.01, bars 0.003; diameter of the medullary shell 0.08; length and thickness of the polar spines 0.04.
Habitat.—Central area of the Pacific, Station 271, depth 2425 fathoms.
5. Lithatractus convallaria, n. sp.
Outer shell thick walled, smooth, with elegant regular network; the meshes circular, six-lobed, rosette-like (of the same form as Stauroxiphos gladius, Pl. 15, fig. 7), twice to three times as broad as the bars; six to eight on the half equator. Proportion of the major axis of the ellipsoid to the minor = 4 : 3. Minor axis twice as long as the diameter of the inner spherical shell, which has regular, simple, circular pores of half the size. Polar spines short and thick, conical, only one-fourth to one-sixth as long as the minor axis, and quite as thick.
Dimensions.—Longer axis of the cortical shell 0.16, shorter axis 0.12; pores 0.016, bars 0.006; diameter of the medullary shell 0.06; length of the polar spines 0.02 to 0.03, basal thickness the same.
Habitat.—Central area of the Pacific, Station 268, depth 2900 fathoms.
Definition.—Network of the outer shell regular, with meshes of equal size and similar form; surface thorny or papillose, covered with small conical spines or tubercles.
6. Lithatractus echiniscus, n. sp.
Outer shell thorny, thin walled, with regular network; meshes circular, with hexagonal frame, four to five times as broad as the thin bars; eighteen to twenty on the half equator. From every corner between the three meshes, where three hexagons unite, starts one short, straight, triangular thorn (as in Ellipsoxiphus elegans, Pl. 14, fig. 7). Proportion of the major axis of the ellipsoid to the minor = 4 : 3. Minor axis twice the diameter of the inner spherical shell, the pores of which are half as broad, circular. Polar spines three-sided pyramidal, about as long as the minor axis, as broad at the base as one hexagonal frame.
Dimensions.—Longer axis of the cortical shell 0.08, shorter axis = 0.06; pores 0.004, bars 0.001; length of the polar spines 0.05, basal thickness 0.005; diameter of the inner shell 0.03.
Habitat.—South Atlantic, off Tristan da Cunha, Station 334, surface.
7. Lithatractus carduelis, n. sp.
Outer shell thin walled, thorny, with regular network; meshes circular, simple, four to six times as broad as the thin bars; ten to twelve on the half equator. Between every three meshes is one short conical spine. Proportion of the major axis to the minor = 6 : 5. Minor axis equals three times the diameter of the inner spherical shell. Polar spines conical, thick, half as long as the major axis, thicker at the base than one pore. (This species differs from Stylatractus carduus only by the simple medullary shell.)
Dimensions.—Longer axis of the ellipsoid 0.12 to 0.16, shorter axis 0.1 to 0.14; pores 0.02 to 0.03, bars 0.005; length of the polar spines 0.05 to 0.10, basal breadth 0.04; diameter of the medullary shell 0.03 to 0.04.
Habitat.—Central area of the Pacific, Stations 268 to 274, depth 2350 to 2900 fathoms; also fossil in the rocks of Barbados.
8. Lithatractus cirsium, n. sp.
Outer shell thin walled, thorny, with regular network; pores circular, simple, small, two to three times as broad as the thin bars; eighteen to twenty-four on the half equator. Proportion of the major axis to the minor = 4 : 3. Inner shell ellipsoidal, half as large as the outer. Polar spines cylindrical, blunt, thin, very variable in length (one-fourth to three-fourths of the major axis, not thicker than a mesh).
Dimensions.—Longer axis of the ellipsoid 0.07 to 0.09, shorter axis 0.05 to 0.07; pores 0.005 to 0.006, bars 0.002; length of the polar spines 0.02 to 0.06, basal breadth 0.004; length of the inner shell 0.04, breadth 0.03.
Habitat.—North Pacific, Station 244, surface.
9. Lithatractus rosetta, n. sp.
Outer shell thick walled, thorny, with regular network; meshes circular, funnel-shaped, its outer aperture elegant, rosette-like, with eight to ten incisions (like Stylosphæra calliope, Pl. 16, fig. 6); eight to ten meshes on the half equator, three to four times as broad as the bars. Proportion of the longer axis to the shorter = 5 : 4. Shorter axis equals three times the diameter of the inner spherical shell. Polar spines three-sided pyramidal, about half as long as the shorter axis, as broad at the base as a mesh.
Dimensions.—Longer axis of the cortical shell 0.15, shorter 0.12; pores 0.02, bars 0.005; length of the polar spines 0.05, basal breadth 0.02; diameter of the inner shell 0.04.
Habitat.—South-eastern part of the Pacific, Station 302, depth 1450 fathoms.
Definition.—Network of the outer shell irregular, with meshes of unequal size or dissimilar form; surface smooth, without thorns or papillæ.
10. Lithatractus conifer, n. sp.
Outer shell thin walled, smooth, with irregular, roundish pores, two to four times as broad as the thin bars; fifteen to twenty on the half equator. Margin of the pores simple. Proportion of the major axis to the minor = 3 : 2. Minor axis twice as large as the diameter of the inner spherical shell, the pores of which are also irregular, roundish, but of half the size. Polar spines conical, somewhat shorter than the main axis, on the base two to three times as thick as a large pore.
Dimensions.—Longer axis of the outer shell 0.15, shorter axis 0.1; pores 0.002 to 0.004, bars 0.001; diameter of the inner shell 0.05; length of the polar spines 0.12, basal breadth 0.012.
Habitat.—South Atlantic, Station 325, surface.
11. Lithatractus lobatus, n. sp.
Outer shell thick walled, smooth, with irregular, roundish pores, four to eight times as broad as the bars; six to eight on the half equator. Margin of the pores lobed, very irregular, bluntly dentate, by five to twenty slight incisions. Proportion of the major axis to the minor very variable, between 3 : 2 and 9 : 8. Diameter of the inner shell also variable, between one-third and one-half of the outer; pores of the former scarcely half the size of the latter, simple, roundish, or circular. The inner shell is at some parts quite spherical, at other parts more or less ellipsoidal. Polar spines conical, very variable in size and form, sometimes in the basal half triangular; they are sometimes somewhat longer than the main axis, at other times considerably shorter; their basal breadth is occasionally the same as that of the largest pores, sometimes, however, scarcely half as large. This deep-sea species is very common in the central area of the Tropical Pacific (Stations 266 to 272), and occurs also fossil in the Barbados deposits. It is interesting from its great variability, and sometimes constitutes a transitional form to Stylosphæra.
Dimensions.—Longer axis of the outer shell 0.1 to 0.15, shorter axis 0.05 to 0.12; pores 0.018 to 0.024, bars 0.002 to 0.004; diameter of the inner shell 0.04 to 0.08; length of the polar spines 0.08 to 0.2, basal thickness 0.01 to 0.02.
Habitat.—Central area of the Pacific, common; Stations 266 to 272, depth 2425 to 2900 fathoms; also fossil in Barbados.
12. Lithatractus jugatus, n. sp. (Pl. 16, fig. 2).
Stylosphæra jugata, Haeckel, 1881, Prodromus et Atlas (pl. xvi. fig. 2).
Outer shell thick walled, smooth, or somewhat reticulated, with a peculiar, irregular, double network. The pores are roundish, of very different sizes, with double margin of the outer aperture, and so irregularly distributed in polygonal groups that every group contains two to six pores immediately touching each other; the groups are separated by broader bars. On the half equator of the shell are about six to eight groups and twelve to eighteen pores. Proportion of the longer axis of the ellipsoidal shell to the shorter = 6 : 5 or 5 : 4. Inner ellipsoidal shell about half the size; its pores are not easy to make out. Polar spines three-sided pyramidal, with prominent edges, about half as long as the major axis, as broad at the base as a group of pores. (Nearly allied to Stylosphæra jugata, p. 137.)
Dimensions.—Longer axis of the cortical shell 0.12 to 0.16, shorter axis 0.1 to 0.13; pores 0.01 to 0.02; length of the polar spines 0.06 to 0.08, basal breadth 0.03 to 0.4.
Habitat.—Central area of the Pacific, Stations 266 to 272, depth 2425 to 2900 fathoms.
Definition.—Network of the outer shell irregular, with meshes of unequal size or dissimilar form; surface thorny or papillose, covered with small conical spines or tubercles.
13. Lithatractus conostylus, n. sp.
Outer shell thorny, thin walled, with irregular network; pores roundish, of unequal size, twice to four times as broad as the thin bars; sixteen to twenty on the half equator. Proportion of the longer axis to the shorter = 5 : 4. Shorter axis twice the diameter of the inner spherical shell. Polar spines conical, very stout, longer than the main axis, its base equals one-third of the minor axis.
Dimensions.—Major axis of the cortical shell 0.1, shorter axis 0.08; pores 0.004 to 0.002, bars 0.001; diameter of the medullary shell 0.04; polar spines—length 0.12, thickness 0.03.
Habitat.—Central area of the Pacific, Station 271, depth 2425 fathoms.
14. Lithatractus gamoporus, n. sp.
Outer shell thorny, thick walled, with irregular network; pores roundish, of unequal size, so irregularly distributed in polygonal groups that in every group two to six pores (commonly three to four) are near together; the groups are separated by broader bars. On the half equator six to eight groups and eighteen to twenty-four pores. Proportion of the longer axis to the shorter = 6 : 5. Shorter axis equals twice the diameter of the inner ellipsoidal shell. Polar spines three-sided pyramidal, about as long as the equatorial axis, as broad at the base as a group of pores.
Dimensions.—Major axis of the cortical shell 0.12, minor axis 0.1; pores 0.004 to 0.012, bars 0.003; length of the polar spines 0.1, basal breadth 0.03.
Habitat.—Central area of the Pacific, Stations 271 to 274, depth 2350 to 2750 fathoms.
Definition.—Druppulida with simple ellipsoidal cortical shell and simple medullary shell, with two large opposite polar spines in the main axis of different size or dissimilar form.
The genus Druppatractus differs from its near relation Lithatractus in the differentiation of the two polar spines, which are different in size or form, often to a very considerable degree. It has therefore the same relation to the latter that Ellipsoxiphus bears to Ellipsostylus.
Definition.—Network of the cortical shell regular or subregular, with meshes of nearly equal size and similar form; surface smooth, without thorns or papillæ.
1. Druppatractus ichthydium, n. sp.
Cortical shell thin walled, with smooth surface and regular network. Proportion of the major axis to the minor = 3 : 2. Pores circular, hexagonally framed, twice as broad as the bars; seven to eight on the half equator (as in Xiphostylus alcedo, Pl. 13, fig. 4). Medullary shell spherical, one-third as broad as the cortical shell. Polar spines straight, three-sided pyramidal, as broad at the base as one mesh; the longer equals the main axis of the cortical shell, the shorter only its half.
Dimensions.—Major axis of the ellipsoidal cortical shell 0.18, minor axis 0.12; pores 0.01, bars 0.005; diameter of the medullary shell 0.04; length of the major polar spine 0.16 to 0.2, of the minor 0.01 to 0.12, basal breadth 0.01.
Habitat.—Mediterranean (Corfu), surface, Haeckel.
2. Druppatractus hippocampus, n. sp. (Pl. 16, figs. 10, 11).
Stylosphæra hippocampus, Haeckel, 1881, Atlas, pl. xvi. figs. 10, 11.
Cortical shell thick walled, with smooth surface and regular network. Proportion of both axes = 7 : 6. Pores circular, hexagonally lobed, three times as broad as the bars; nine to ten on the half equator. Medullary shell ellipsoidal, nearly half as large as the cortical. Larger polar spine horn-like curved, as long as the main axis, smaller scarcely half as long, pommel-shaped.
Dimensions.—Major axis 0.09, minor 0.075; pores 0.01, bars 0.003; axes of the medullary shell 0.04 and 0.03; length of the larger polar spine 0.06 to 0.09, of the smaller 0.04, basal breadth 0.02.
Habitat.—Pacific, central area, Stations 270 to 272, surface.
3. Druppatractus belone, n. sp.
Cortical shell thin walled, with smooth surface and regular network. Proportion of both axes = 4 : 3. Pores circular, twice as broad as the bars; ten to twelve on the half equator. Medullary shell spherical, one-third as broad as the cortical shell. Polar spines strong, straight, cylindrical, with conical apex, as broad at the base as two pores; the larger once and a half to twice as long as the main axis, the smaller only one-third to one-fourth as long.
Dimensions.—Major axis 0.1 to 0.12, minor 0.08 to 0.09; pores 0.008, bars 0.004; diameter of the medullary shell 0.03; length of the larger polar spine 0.15 to 0.2, of the minor 0.04 to 0.05, basal thickness of them 0.02.
Habitat.—Cosmopolitan; Atlantic, Indian, and Pacific, surface.
4. Druppatractus testudo, Haeckel.
Stylosphæra testudo, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 299, Taf. viii. fig. 16.
Cortical shell thick walled, spindle-shaped, with smooth surface and regular network. Proportion of the two axes = 3 : 2. Pores circular, five times as broad as the bars; only six to seven on the half equator. Medullary shell ellipsoidal, about one-third as large as the cortical shell. Polar spines strong, short, three-sided pyramidal; the larger as long as half the transverse axis, the smaller only one-fourth as long.
Dimensions.—Major axis 0.12, minor 0.8; pores 0.015, bars 0.003; axes of the medullary shell 0.04 and 0.03; length of the larger polar spine 0.04, of the smaller 0.02, basal thickness 0.01.
Habitat.—Pacific, Philippine and Californian Sea (Ehrenberg), Stations 244, 266, 289, &c., depth 2550 to 2900 fathoms.
Definition.—Network of the cortical shell regular or subregular, with meshes of nearly equal size and similar form; surface thorny or papillose, covered with small conical spines or tubercles.
5. Druppatractus accipenser, n. sp.
Cortical shell thick walled, thorny, with regular network. Proportion of the two axes = 6 : 5. Pores circular, each with a six-lobed outer opening, funnel-shaped, twice as broad as the bars; nine to ten on the half equator. Medullary shell spherical, one-third as broad as the cortical shell. Polar spines very strong, three-sided pyramidal, as broad at the base as three pores; the larger about as long as the main axis, the smaller only one-third as long.
Dimensions.—Major axis 0.12, minor 0.1; pores 0.01, bars 0.005; medullary shell 0.035; length of the larger polar spine 0.11, of the smaller 0.04, basal breadth 0.03.
Habitat.—Indian Ocean, Madagascar, surface, Rabbe.
6. Druppatractus ostracion, n. sp. (Pl. 16, figs. 8, 9).
Cortical shell thick walled, thorny, with regular network. Proportion of the two axes = 4 : 3. Pores circular, hexagonally framed, three to four times as broad as the crested bars; from every corner of the hexagon (between three meshes) arises a short papilla; the bottom of every funnel-like mesh is closed by a very thin plate with three regular, circular pores (occasionally four), sometimes confluent, at other times separate. Medullary shell (fig. 9) half as large as the cortical, ellipsoidal and papillate, with regular, circular pores. Polar spines very strong, three-sided prismatic, often somewhat irregular, with short apex; the larger once to twice as long as the main axis, the smaller scarcely half as long.
Dimensions.—Major axis 0.16, minor 0.12; pores 0.02 (porules at their base 0.01), bars 0.006; axes of the medullary shell 0.07 and 0.06, its pores 0.01, bars 0.003; length of the larger polar spine 0.15 to 0.3, of the smaller 0.07 to 0.09, basal thickness 0.03.
Habitat.—Pacific, central area, Station 265, depth 2900 fathoms.
7. Druppatractus coronatus, Haeckel.
Stylosphæra coronata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xxv. fig. 4.
Cortical shell thick walled, thorny, with regular network. Proportion of the two axes = 5 : 4. Pores circular, simple, twice as broad as the bars; eight to ten on the half equator. Medullary shell circular, one-third as broad as the cortical shell. Polar spines furrowed and angular; the longer and thinner pyramidal about as long as the main axis, the shorter and thicker scarcely half as long, thickened towards the short conical apex.
Dimensions.—Major axis 0.08 to 0.1, minor 0.06 to 0.08; pores 0.01, bars 0.005; diameter of the medullary shell 0.03; length of the large polar spine 0.08 to 0.12, of the shorter 0.04 to 0.05.
Habitat.—Fossil in the Tertiary rocks of Barbados; also living in the depths of the Pacific, central area, Stations 265 to 268, depth 2700 to 2900 fathoms.
Definition.—Network of the cortical shell irregular, with meshes of unequal size or dissimilar form; surface smooth, without thorns or papillæ.
8. Druppatractus lævis, Haeckel.
Stylosphæra lævis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xxv. fig. 6.
Cortical shell thin walled, smooth, with irregular network. Proportion of the two axes = 3 : 2. Pores roundish or subcircular, of different size, one-half to twice as broad as the bars; eight to ten on the half equator. Medullary shell ellipsoidal, one-third as large as the cortical shell. Polar spines conical, the larger and thinner nearly as long as the main axis, the shorter and thicker scarcely one-third as long.
Dimensions.—Major axis 0.07 to 0.1, minor 0.05 to 0.07; pores and bars 0.005 to 0.01; axes of the medullary shell 0.03 and 0.02; length of the major polar spine 0.06 to 0.09, of the shorter 0.03 to 0.04.
Habitat.—Cosmopolitan; Atlantic, Indian, Pacific, surface.
9. Druppatractus xiphias, n. sp.
Cortical shell thick walled, smooth, with irregular network. Proportion of the two axes = 6 : 5. Pores funnel-shaped, composed of two to four confluent smaller porules, twice to four times as broad as the bars; ten to twelve on the half equator. Medullary shell spherical, half as broad. Polar spines three-sided pyramidal, the larger about as long as the main axis, the shorter one-third to one-half as long.
Dimensions.—Major axis 0.12, minor 0.1; pores 0.012 to 0.018, bars 0.004; diameter of the medullary shell 0.05; length of the major polar spine 0.1, of the minor 0.03 to 0.05.
Habitat.—Pacific, central area, Station 268, depth 2900 fathoms.
Definition.—Network of the cortical shell irregular, with meshes of unequal size or dissimilar form; surface thorny or papillose, covered with small spines or tubercles.
10. Druppatractus diodon, n. sp.
Cortical shell thin walled, thorny, with irregular network. Proportion of the two axes = 5 : 4. Pores simple, irregular, roundish, twice to four times as broad as the bars; eight to ten on the half equator. Medullary shell spherical, half as broad. Polar spines conical, more or less curved; the major longer than the main axis, the minor scarcely half as long. (Resembles Sphærostylus ophidium, Pl. 16, figs. 14, 15, but differs from it in the prolongation of the main axis.)
Dimensions.—Major axis 0.15, minor 0.12; pores 0.01 to 0.02, bars 0.005; diameter of the medullary shell 0.06; length of the larger polar spine 0.12 to 0.18, of the shorter 0.06 to 0.08, basal thickness 0.003.
Habitat.—Pacific, central area, Station 274, surface.
11. Druppatractus pisciculus, n. sp.
Cortical shell thick walled, spiny, with irregular network. Proportion of the two axes = 3 : 2. Pores irregular, roundish, lobed, or composed of three to five confluent porules, twice to six times as broad as the bars; six to eight on the half equator. (Similar to Ellipsoxiphus atractus, Pl. 14, fig. 1.) Medullary shell ellipsoidal, nearly half as large as the cortical shell. Polar spines three-sided pyramidal, the major longer than the main axis, the minor scarcely one-third to one-fourth as long.
Dimensions.—Major axis 0.18, minor 0.12; pores 0.01 to 0.03, bars 0.004; axes of the medullary shell 0.08 and 0.05; length of the major polar spine 0.2, of the minor 0.05, basal breadth 0.02.
Habitat.—South Atlantic, Station 332, depth 2200 fathoms.
Definition.—Druppulida with simple ellipsoidal cortical shell and double medullary shell, in the main axis with two large opposite polar spines of equal size and similar form.
The genus Stylatractus differs from Lithatractus in the double medullary shell, from Amphisphæra in the ellipsoidal form of the cortical shell. As in these two genera, both opposite polar spines have the same shape and size.
Definition.—Network of the cortical shell regular or subregular, with meshes of nearly equal size and similar form; surface smooth, without thorns or papillæ.
1. Stylatractus neptunus, n. sp. (Pl. 17, fig. 6).