1. Hexalonche phænaxonia, n. sp.
Cortical shell thin walled, smooth; its pores regular, hexagonal, six to eight times as broad as the bars; eight to ten to twelve on the radius. Medullary shell one-third as broad, with regular, hexagonal pores of half size. Six spines triangular pyramidal, as long as the radius of the shell, at the base as broad as one pore. (Differs from Hexastylus phænaxonius, Pl. 21, fig. 3, only in the medullary shell and the six inner radial beams, connecting it with the cortical shell.)
Dimensions.—Diameter of the outer shell 0.15, pores 0.01 to 0.015, bars 0.015 to 0.02; inner shell 0.05; length of the spines 0.08, basal breadth 0.01.
Habitat.—Central Pacific, Stations 266 to 271, depth 2425 to 2925 fathoms.
2. Hexalonche rosetta, n. sp. (Pl. 25, figs. 3, 3a, 3b).
Cortical shell thick walled, smooth, two and a half time as broad as the medullary shell. Pores of the latter (fig. 3a) regular circular; eight to ten on the half meridian, about as broad as the bars between them. Pores of the outer shell regular, hexagonal, remarkable for a very peculiar form and arrangement. In the transverse section of the shell (fig. 3b) they appear as narrow, hexagonal prismatic canals, twice as high as broad, and four to five times as broad as the thin elevated bars between them. Every seven meshes form together a larger, regular hexagon (six pores surrounding one central pore). The periphery of these larger, rosette-like hexagons projects more strongly from the surface than the walls between the smaller hexagons. On the half meridian of the shell may be counted six to seven larger and eighteen to twenty smaller hexagons. The six radial beams between the two shells are thin, three-sided prismatic, not broader than the bars of the network, the prominent prolongations of which form six very strong spines of peculiar club-like shape (fig. 3), as long as the radius of the outer shell. The three wings of the club are lower in the inner, higher in the outer half; the broadest part of the spine (at the base and in the outer third) is as broad as a hexagonal rosette (equal to three meshes of the outer shell); its outer apex is pyramidal.
Dimensions.—Diameter of the outer shell 0.13, pores 0.008 to 0.01, bars 0.02; inner shell 0.05; length of the spines 0.07, distal breadth 0.03.
Habitat.—Tropical West Pacific, Station 225, depth 4475 fathoms.
3. Hexalonche favosa, n. sp.
Cortical shell thick walled, smooth, four times as broad as the medullary shell. Pores of the former regular circular, hexagonally framed, deep funnel-shaped, of the same breadth as the bars; six to eight on the radius. Six spines triangular-pyramidal, as long as the radius, at the base twice as broad as one pore. (Differs from the similar Hexastylus favosus mainly in the possession of a medullary shell.)
Dimensions.—Diameter of the outer shell 0.16, pores and bars 0.012; inner shell 0.04; length of the spines 0.08, basal breadth 0.025.
Habitat.—Equatorial Atlantic, Station 348, depth 2450 fathoms; also fossil in Barbados.
4. Hexalonche octahedra, n. sp. (Pl. 22, figs. 8, 8a).
Cortical shell a regular octahedron, thin walled, with twelve more or less rounded edges (between the bases of the spines), and with smooth surface, three times as broad as the spherical medullary shell. Pores of the former regular circular (three times as large as those of the latter), four times as broad as the bars; five to seven on the radius. Six spines three-sided prismatic, with thickened base and cuspidated end, somewhat longer than the radius, and once to twice as broad as one pore.
Dimensions.—Diameter of the outer shell 0.11, pores 0.01, bars 0.0025; inner shell 0.04; length of the spines 0.08, bars 0.01.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
5. Hexalonche conicornis, n. sp. (Pl. 22, fig. 2).
Cortical shell thick walled, smooth, three times as broad as the medullary shell. Pores of both spheres regular circular, three to four times as broad as the bars; those of the thick walled outer shell six to seven on the radius, twice as large as those of the thin walled inner shell; six radial beams between the two spheres, very thin, cylindrical; six spines short, conical, scarcely as long as the radius of the outer shell, at the base twice as broad as one pore.
Dimensions.—Diameter of the outer shell 0.12 to 0.14, pores 0.01, bars 0.003; inner shell 0.04 to 0.05; length of the spines 0.04 to 0.06, basal breadth 0.02.
Habitat.—Central Pacific, Station 268, depth 2900 fathoms.
6. Hexalonche curvicornis, n. sp. (Pl. 25, fig. 4).
Cortical shell thick walled, smooth, not much larger than the medullary shell (= 4 : 3). Pores of both spheres regular circular, nearly of the same size, three times as broad as the bars between them; seven to nine on the radius. Six spines three-sided prismatic, inside and outside of the exterior shell of equal thickness, twice as broad as one pore, longer than the diameter of the outer shell, and in a singular manner curved like an ox horn; the three edges of each horn somewhat spirally twisted.
Dimensions.—Diameter of the outer shell 0.16, pores 0.01, bars 0.003; inner shell 0.12; length of the spines 0.2, breadth 0.02.
Habitat.—Central Pacific, Station 266, depth 2750 fathoms.
7. Hexalonche brevicornis, n. sp.
Cortical shell thin walled, smooth, three times as broad as the medullary shell. Pores of the former regular circular, double-edged, six to eight times as broad as the thin bars, five to six on the radius. Six spines triangular pyramidal, as broad as one pore and only twice as long.
Dimensions.—Diameter of the outer shell 0.14, pores 0.02, bars 0.003; inner shell 0.045; length of the spines 0.05, basal breadth 0.02.
Habitat.—North Pacific, Station 253, depth 3125 fathoms.
8. Hexalonche grandis, n. sp.
Cortical shell thick walled, smooth, four times as broad as the medullary shell. Pores of the outer shell regular circular, four times as broad as the bars; thirteen to fifteen on the radius. Six spines conical, scarcely half as long as the radius, at the base as broad as one pore.
Dimensions.—Diameter of the outer shell 0.2 to 0.32, pores 0.01 to 0.02, bars 0.003 to 0.005; inner shell 0.06 to 0.08; length of the spines 0.06, breadth 0.02.
Habitat.—Central Pacific, Station 268, depth 2900 fathoms.
Definition.—Pores of the cortical shell regular or subregular, of nearly equal size and similar form; surface covered with numerous conical or bristle-shaped radial by-spines.
9. Hexalonche amphisiphon, n. sp. (Pl. 25, figs. 2, 2a, 2b).
Cortical shell thin walled, armed with very numerous bristle-shaped, radial by-spines, a quarter to a half as long as the six main spines. Pores regular hexagonal, twelve to fourteen on the radius, with very thin bars, prolonged on the outer as well as the inner surface into a short truncated conical tube (Pl. 25, fig. 2b). Medullary shell octahedral, with irregular polygonal meshes and very thin bars between them (fig. 2a), connected with the outer (six to eight times larger) shell by six very thin radial beams. These are prolonged outside into six strong pyramidal spines, nearly as long as the diameter of the outer shell, with sharp straight edges, at the base twice as broad as one pore.
Dimensions.—Diameter of the outer shell 0.15, pores 0.01, bars 0.001; inner shell 0.02; length of the spines 0.12, basal breadth 0.02.
Habitat.—Central Pacific, Station 271, surface.
10. Hexalonche anaximandri, n. sp. (Pl. 22, fig. 5).
Cortical shell thin walled, covered with short conical spines (smaller than the pores), three times as broad as the medullary shell. Pores of the outer shell subregular hexagonal, four times as broad as the bars; five to seven on the radius. Inner shell with regular hexagonal pores of half the size, connected with the outer by six strong, three-sided prismatic beams, which are prolonged outside into six very stout pyramidal spines, with three prominent edges, longer than the radius and twice as broad as one pore.
Dimensions.—Diameter of the outer shell 0.12, pores 0.01, bars 0.0025; inner shell 0.04; length of the spines 0.07, basal breadth 0.02.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
11. Hexalonche octocolpa, n. sp. (Pl. 22, figs. 6, 6a).
Cortical shell thin walled, nearly octahedral, with eight hemispherical or bosom-shaped vaultings, corresponding to the eight faces of a regular octahedron, the three axes of which are indicated by the six spines. Surface covered with short bristle-shaped spines. Pores regular hexagonal, ten to fifteen times as broad as the thin bars; seven to nine on the radius. Medullary shell (fig. 6a) spherical, with regular circular pores, one-third as broad as the cortical shell, and connected with it by six strong triangular radial beams, which are prolonged outside into pyramidal spines, one-third as long as the shell diameter.
Dimensions.—Diameter of the outer shell 0.2, pores 0.03, bars 0.002; inner shell 0.06; length of the spines 0.06, breadth 0.02.
Habitat.—Central Pacific, Station 274, depth 2750 fathoms.
12. Hexalonche cristata, n. sp.
Cortical shell thick walled, four times as broad as the medullary shell, and covered with short conical spines arising from the nodal points of elevated crests which form regular hexagonal frames around the funnel-shaped circular pores. These are two to three times as broad as the crested bars; eight to ten on the radius. Six spines three-sided pyramidal, with strong prominent edges, about as long as the radius of the shell.
Dimensions.—Diameter of the outer shell 0.16 to 0.2, pores 0.01 to 0.015, bars 0.003 to 0.005; inner shell 0.04 to 0.05; length of the spines 0.08 to 0.12, basal breadth 0.01 to 0.03.
Habitat.—Central Pacific, Station 266 to 274, depth 2350 to 2925 fathoms.
13. Hexalonche serrata, n. sp.
Cortical shell thick walled, four times as broad as the medullary shell, with spiny surface. Pores regular circular, twice as broad as the bars, five to seven on the radius, funnel-shaped, separated by hexagonal frames, the sharp crests of which are serrated; at the nodal-points longer bristle-shaped by-spines. Six main spines triangular prismatic, longer than the diameter of the shell, twice as broad as one pore.
Dimensions.—Diameter of the outer shell 0.15, pores 0.01, bars 0.005; inner shell 0.04; length of the spines 0.2, breadth 0.02.
Habitat.—South Atlantic, Station 332, depth 2200 fathoms.
14. Hexalonche anaximenis, n. sp. (Pl. 25, fig. 5).
Cortical shell thin walled, twice as broad as the medullary shell, and covered with short conical by-spines. Pores regular circular, twice as broad as the bars; five to six on the radius. Circular pores of the medullary shell one-third as broad. Radial main spines conical, nearly as long as the radius of the shell.
Dimensions.—Diameter of the outer shell 0.1, pores 0.01, bars 0.005; inner shell 0.05; length of the spines 0.04, basal breadth 0.015.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
15. Hexalonche aspera, n. sp.
Cortical shell thin walled, three times as broad as the medullary shell, and covered with short conical spines. Pores regular circular, four to six times as broad as the bars; eight to ten on the radius. Radial spines conical, about as long as the diameter of the shell.
Dimensions.—Diameter of the outer shell 0.12, pores 0.08, bars 0.0015; inner shell 0.04; length of the spines 0.1, basal breadth 0.02.
Habitat.—South Pacific, Station 300, depth 1375 fathoms.
16. Hexalonche castanella, n. sp.
Cortical shell thick walled, five times as broad as the medullary shell, and covered with numerous short conical spines. Pores regular circular, twice as broad as the bars; ten to twelve on the radius. Radial spines triangular pyramidal, about as long as the radius of the shell.
Dimensions.—Diameter of the outer shell 0.22, pores 0.01, bars 0.005; inner shell 0.045; length of the spines 0.12, basal breadth 0.02.
Habitat.—North Atlantic, Station 353, depth 3125 fathoms.
Definition.—Pores of the cortical shell irregular, of unequal size or form; surface smooth, without radial by-spines (other than the six main spines).
17. Hexalonche hexacantha, Haeckel.
Haliomma hexacanthum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 35, Taf. iv. fig. 5.
Haliomma hexacanthum, Haeckel, 1862, Monogr. d. Radiol., p. 430.
Cortical shell thin walled, smooth, with irregular polygonal pores (commonly hexagonal or pentagonal), two to three times as broad as the bars; eight to ten on the radius. Medullary shell one quarter as broad, connected with the former by six thin radial beams which are prolonged outside into six triangular pyramidal spines (not quadrangular, as Müller describes), longer than the radius of the shell.
Dimensions.—Diameter of the outer shell 0.2, pores 0.01 to 0.015, bars 0.005; inner shell 0.05; length of the spines 0.15, basal breadth 0.015.
Habitat.—Mediterranean (Messina, Nice, Genoa).
18. Hexalonche geometrica, n. sp.
Cortical shell thick walled, smooth, with very peculiar geometrical formation of its network, the pores of which are of very different size and form, but highly regular disposition. Each of the six triangular spines is surrounded at the base by three small roundish pores (between the three wings of its base), and further by a coronal of six very large pores, three of which are pentagonal, and the other three (alternating) heptagonal. The six basal coronals are separated by irregular smaller pores. Medullary shell thin walled, with regular hexagonal pores (three on the radius) and thin bars, connected with the outer shell by six thin triangular prismatic radial beams, which are prolonged outside into short pyramidal spines (half as long as the radius).
Dimensions.—Diameter of the outer shell 0.2, thirty-six larger pores of the coronals 0.03 to 0.04, smaller pores between them 0.01 to 0.02, bars 0.005; inner shell 0.05 (with pores of 0.008); length of the spines 0.05, basal breadth 0.03.
Habitat.—South Atlantic, off Buenos Ayres, Station 323, depth 1900 fathoms.
19. Hexalonche pythagoræa, n. sp. (Pl. 22, fig. 1).
Cortical shell thick walled, smooth, three times as broad as the medullary shell. Pores irregular roundish, twice to eight times as broad as the bars, of very different size; usually in the space between every three spines are three or six larger pores, separated by numerous smaller pores (often the disposition of the larger pores is much more regular than in the figured specimen). Medullary shell with regular circular pores, connected with the outer by six very thin radial beams, which are prolonged outside into six short triangular pyramidal spines about as long and broad as the half radius.
Dimensions.—Diameter of the outer shell 0.12, pores 0.008 to 0.03, bars 0.004; inner shell 0.04; length of the spines 0.04, basal breadth 0.03.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.
20. Hexalonche aristarchi, n. sp. (Pl. 22, fig. 3).
Cortical shell thin walled, smooth, four times as broad as the medullary shell. Pores irregular polygonal, of very variable size and form, twice to six times as broad as the bars; six to ten on the radius. Medullary shell with regular hexagonal pores, connected with the outer by six very thin radial beams, which are prolonged outside into six triangular pyramidal spines, nearly as long as the radius.
Dimensions.—Diameter of the outer shell 0.1, pores 0.005 to 0.02, bars 0.003; inner shell 0.025; length of the spines 0.05, basal breadth 0.01.
Habitat.—North Pacific, Station 241, depth 2300 fathoms.
21. Hexalonche ekphantæa, n. sp.
Cortical shell thin walled, smooth, four times as broad as the medullary shell. Pores irregular roundish, of very variable size and form, twice to six times as broad as the bars, ten to fifteen on the radius. Six spines cylindro-conical, longer than the diameter of the shell.
Dimensions.—Diameter of the outer shell 0.2, pores 0.004 to 0.012, bars 0.002; inner shell 0.05; length of the spine 0.3, basal breadth 0.01.
Habitat.—Indian Ocean, Sunda Strait, surface, Rabbe.
Definition.—Pores of the cortical shell irregular, of different size or form; surface covered with numerous conical or bristle-shaped, radial by-spines.
22. Hexalonche philosophica, n. sp. (Pl. 22, fig. 4).
Cortical shell thin walled, covered with short conical spines, three times as broad as the medullary shell. Pores irregular polygonal, or more roundish, twice to six times as broad as the bars; six to eight on the radius. Inner shell of the same structure, pores three times smaller, connected with the outer by six very thin radial beams, which are prolonged outside into six strong, triangular pyramidal spines, as long as the radius. (Similar to Hexalonche anaximandri, Pl. 22, fig. 5, but different in the irregular network and the shorter by-spines.)
Dimensions.—Diameter of the outer shell 0.11, pores 0.005 to 0.015, bars 0.0025; inner shell 0.04; length of the spines 0.06, breadth 0.02.
Habitat.—North Atlantic, Færöe Channel, John Murray; Iceland, Krabbe, surface.
23. Hexalonche seleuci, n. sp.
Cortical shell thick walled, covered with numerous short, bristle-shaped spines. Pores of very different size and form, and of a peculiar, subregular disposition, similar to those of Hexalonche geometrica (though in this case more regular). Each of the six triangular main spines (which reach nearly the length of the radius) is surrounded at the base by three small roundish pores, and these are further supplemented by a coronal of six very large polygonal pores; the six coronals are separated by irregular rows of smaller pores. Inner shell equal to one-third of the outer. Six main spines pyramidal, as long as the radius.
Dimensions.—Diameter of the outer shell 0.16, larger pores 0.03 to 0.04, smaller pores 0.01 to 0.02, bars 0.05 to 0.01; inner shell 0.05; length of the spines 0.08, basal breadth 0.03.
Habitat.—North Atlantic, Station 354, surface.
24. Hexalonche sexaculeata, Haeckel.
Haliomma sexaculeatum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 87, Taf. i. fig. 8.
Cortical shell thick walled, twice as broad as the medullary shell, and covered with short conical spines. Pores irregular polygonal (mostly hexagonal), twice to three times as broad as the bars; six to eight on the radius. Six spines triangular-pyramidal (not quadrangular), somewhat longer than the radius of the shell.
Dimensions.—Diameter of the outer shell 0.11, pores 0.06 to 0.08, bars 0.03; inner shell 0.06; length of the spines 0.07, basal breadth 0.015.
Habitat.—Fossil in Tertiary rocks of Sicily, Grotte, Caltanisetta.
25. Hexalonche heracliti, n. sp. (Pl. 22, fig. 7).
Cortical shell thick walled, covered with bunches of small spines, each bunch at the nodule point between every three pores composed of four to eight conical spinules. Pores irregular roundish, twice to four times as broad as the bars; four to six on the radius. Inner shell equal to one-third of the outer, connected with it by six thin radial beams, which are prolonged outside into six strong triangular spines about as long as the radius.
Dimensions.—Diameter of the outer shell 0.15, pores 0.015 to 0.03, bars 0.08; inner shell 0.05; length of the spines 0.06, basal breadth 0.02.
Habitat.—Indian Ocean, Madagascar, Rabbe, surface.
26. Hexalonche xenophanis, n. sp.
Cortical shell thin walled, covered with numerous short conical spines, four times as broad as the medullary shell. Pores irregular circular, twice to eight times as broad as the bars; five to seven on the radius. Six spines conical or more cylindrical, as long as the diameter of the shell or longer.
Dimensions.—Diameter of the outer shell 0.16 to 0.24, pores 0.01 to 0.04, bars 0.005; inner shell 0.04 to 0.06; length of the spines 0.2 to 0.3, breadth 0.02.
Habitat.—Central Pacific, Stations 266 to 272, surface.
27. Hexalonche setosa, n. sp.
Cortical shell thin walled, covered with numerous bristle-shaped spines, half as long as the six main spines. Pores irregular roundish, twice to five times as broad as the bars; ten to twelve on the radius. Inner shell equal to one-fifth of the outer. Six spines conical, as long as the radius.
Dimensions.—Diameter of the outer shell 0.25, pores 0.008 to 0.02, bars 0.004; inner shell 0.05; length of the spines 0.12, basal breadth 0.03.
Habitat.—South Pacific, Station 291, surface.
28. Hexalonche hystricina, n. sp. (Pl. 25, fig. 6).
Cortical shell thick walled, covered with numerous bristle-shaped spines, half as long as the six main spines. Pores irregular roundish, twice to four times as broad as the bars; five to seven on the radius. Medullary shell with very small circular pores, one-fourth of the cortical shell, connected with it by six thin prismatic radial beams, which are prolonged outside into six strong, short, three-sided pyramidal, cuspidated spines, only half as long as the radius of the outer shell.
Dimensions.—Diameter of the outer shell 0.2, pores 0.015 to 0.03, bars 0.008; inner shell 0.05; length of the spines 0.05, basal breadth 0.02.
Habitat.—Indian Ocean, Sunda Strait, surface, Rabbe.
Definition.—Cubosphærida with two concentric lattice-spheres and six branched spines of equal size.
The genus Hexancistra differs from its ancestral form, Hexalonche, in the ramification of the six radial spines. These are very different in the two subgenera; in Hexancora each spine bears only three simple lateral branches, while in Hexapitys there are three rows of verticillate lateral branches on each spine.
Definition.—Each radial spine with three simple lateral branches only (one branch from each edge of the triangular spine).
1. Hexancistra tricuspis, n. sp. (Pl. 22, fig. 9).
Cortical shell thin walled, covered with short conical by-spines, three times as broad as the medullary shell; its pores regular circular, three times as broad as the bars; ten to twelve on the radius. Pores of the medullary shell half as large, also regular circular. The two shells connected by six thin prismatic radial beams, which are prolonged outside into six very stout main spines, three-sided prismatic, as long as the shell diameter, with three thin wing-like edges. Each edge at the distal end prolonged into a strong curved lateral branch.
Dimensions.—Diameter of the outer shell 0.13, inner 0.4; cortical pores 0.01, bars 0.003; medullary pores 0.005, bars 0.003; length of the six spines 0.13, breadth 0.02.
Habitat.—Central Pacific, Station 266, depth 2750 fathoms.
2. Hexancistra ancorata, n. sp.
Cortical shell thick walled, smooth, twice as broad as the medullary shell; its pores regular circular, twice as broad as the bars; six to eight on the radius. Six radial spines, three-sided prismatic, as long as the shell radius, with three recurved lateral branches at the distal end like the three teeth of an anchor.
Dimensions.—Diameter of the outer shell 0.1, inner 0.05; cortical pores 0.006, bars 0.003; length of the six spines 0.05, breadth 0.02.
Habitat.—South Pacific, Station 296, depth 1825 fathoms.
3. Hexancistra triserrata, n. sp. (Pl. 22, fig. 10).
Cortical shell thin walled, thorny, twice to three times as broad as the medullary shell; the two shells connected by six strong triangular beams. Inner shell spherical, with very small, regular, circular pores; ten to twelve on the half meridian. Bars as broad as the pores. Outer shell regularly octahedral, with eight triangular perfectly regular even faces, separated by eight prominent edges; the meshes circular, regular, about twelve to fourteen on the half meridian, two to three times as broad as the bars between them. Six strong radial spines, about as long as the diameter of the outer shell, three-sided prismatic, cuspidate; their three edges prominent, serrate, spirally twisted. Each spine bears about its middle three strong flattened lateral branches, nearly perpendicular to it, not serrated, and slightly curved.
Dimensions.—Diameter of the outer shell 0.13, inner 0.045; pores of the former 0.01, of the latter 0.004; length of the spine 0.12, breadth 0.014.
Habitat.—Central Pacific, Station 274, depth 2750 fathoms.
4. Hexancistra quadricuspis, n. sp. (Pl. 22, fig. 11).
Cortical shell thin walled, covered with short bristle-shaped by-spines, three and a half times as broad as the medullary shell. Pores of the latter regular circular, small; pores of the former three to six times as large, very irregular, roundish, double-edged. Six radial spines, three-sided prismatic, about as long as the shell diameter, with three wing-like, slightly twisted edges, which are prolonged towards the distal end into three curved horn-shaped branches.
Dimensions.—Diameter of the outer shell 0.17, inner 0.05; cortical pores 0.01 to 0.03, bars 0.005; medullary pores 0.003, bars 0.001; length of the spines 0.15, breadth 0.013.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.
Definition.—Each radial spine with three rows of verticillate lateral branches (a row arising from each edge of the spine).
5. Hexancistra mirabilis, n. sp. (Pl. 23, fig. 3).
Hexapitys mirabilis, Haeckel, 1881, Prodromus, p. 451.
Cortical shell very thin walled, three times as broad as the medullary shell. Inner shell spherical, with very delicate, subregular hexagonal meshes; seven to eight on the half diameter. Outer shell octahedral, with irregular polygonal meshes of very different size; on the surface numerous thin accessory radial spines, equal in length to its radius. Six main spines, extremely long and stout, many times longer than the diameter of the outer shell, nearly as broad as the radius of the inner shell, three-sided prismatic, with sharp, prominent, spirally twisted edges; on every edge a great number of thin lateral branches, arranged perpendicularly to it, as long as the diameter of the outer shell, and pinnated by ten to twenty pairs of delicate secondary spinules, biserial and perpendicular to the primary branches. (In the figured specimen the spherical central capsule, between both shells, was well preserved; its nucleus nearly filled the medullary shell. The thick jelly-veil around it was radially striped and octahedral.)
Dimensions.—Diameter of the outer shell 0.13, of the inner 0.05; length of the spines 0.5 to 0.8 or more, breadth 0.02.
Habitat.—Central Pacific, Station 271, surface.
Definition.—Cubosphærida with two concentric lattice-spheres and six simple spines of different sizes; one opposite pair larger than the two others.
The genus Hexaloncharium exhibits the same relation to its ancestral form, Hexalonche, that Hexastylarium bears to Hexastylus. Two opposite spines of one pair are larger than the four others, and correspond to the three axes of a quadratic crystal.
1. Hexaloncharium octahedrum, n. sp.
Cortical shell smooth, three to four times as broad as the spherical medullary shell, each having regular circular pores, twice to three times as broad as the bars. Form of the outer shell not a sphere, but a regular octahedron, with eight congruent, equilateral triangular even faces. Two opposite spines twice as long as the shell diameter, whilst the four others are scarcely equal to it. Basal breadth of all six the same (three times as large as one pore); form, three-sided prismatic, with cuspidate distal end. (Similar to Hexalonche octahedra, Pl. 22, fig. 8, but distinct in the unequal length of the spines.)
Dimensions.—Diameter of the outer shell 0.16, inner 0.045; length of the major spine 0.3, minor 0.12, basal breadth 0.03.
Habitat.—South Atlantic, Station 332, depth 2200 fathoms.
2. Hexaloncharium philosophicum, n. sp.
Cortical shell spherical, covered with short conical by-spines, twice as broad as the medullary shell; both with regular circular pores three to four times as broad as the bars. Two major spines cylindrical, with conical apex, three times as long as the four others, which are conical and about as long as the shell radius; basal breadth of all six the same (equal to one pore). Similar to Hexalonche anaximenis (Pl. 25, fig. 5), but distinct in the enormous prolongation of two opposite spines.
Dimensions.—Diameter of the outer shell 0.12, inner 0.06; length of the two major spines 0.2, of the four minor 0.06, basal breadth 0.02.
Habitat.—Central Pacific, Station 267, depth 2700 fathoms.
3. Hexaloncharium hystricinum, n. sp.
Cortical shell spherical, three times as broad as the medullary shell, and densely covered with oblique bristle-shaped by-spines. Pores irregular roundish. Two opposite major spines three-sided prismatic, longer than the shell diameter; four minor spines pyramidal, scarcely half as long as the shell radius. (Somewhat similar to Hexalonche hystricina, but distinct in the prolongation of two major spines.)
Dimensions.—Diameter of the outer shell 0.15, inner 0.05; length of the two major spines 0.2, four minor 0.03, basal breadth 0.02.
Habitat.—South Pacific, Station 288, surface.
Definition.—Cubosphærida with two concentric lattice-spheres and six simple spines of different sizes in pairs; the two opposite spines of each pair equal, the three pairs unequal.
The genus Hexalonchidium exhibits the same relation to Hexalonche that Hexastylidium bears to Hexastylus; the growth of the three spine-pairs is different, whilst both spines of each pair are equal; they correspond therefore to the three axes of a rhombic crystal.
1. Hexalonchidium axonometrum, n. sp.
Cortical shell thin walled, covered with short bristle-shaped by-spines, twice as broad as the medullary shell; both with regular hexagonal meshes, twice to three times as broad as the bars (inner meshes half as broad as the outer). All three spine-pairs three-sided prismatic, of very different length but of equal breadth (equal to three pores). Major spine-pair twice as long as the shell diameter; middle pair about equal to the latter, minor scarcely half as long. (Similar to Hexalonche anaximandri, Pl. 22, fig. 5, but distinct in the different length of the spines.)
Dimensions.—Diameter of the outer shell 0.12, inner 0.06; length of the major spines 0.25, middle 0.1, minor 0.04.
Habitat.—Indian Ocean, Madagascar, surface, Rabbe.
Definition.—Cubosphærida with three concentric, spherical, or octahedral lattice-shells.
Definition.—Shell with three concentric lattice-spheres and six simple spines of equal size.
The genus Hexacontium, the ancestral form of the Hexacontida, is probably derived from Hexalonche by duplication of the medullary shell. As in the latter, all six spines are of equal size, opposite in pairs in the three dimensive axes, and correspond therefore to the three equal axes of a tesseral crystal.
Definition.—Pores of the cortical shell regular or subregular, of nearly equal size and similar form; surface smooth, without radial spines or papillæ (other than the six main spines).
1. Hexacontium phænaxonium, n. sp.
Cortical shell thin walled, smooth; its pores regular hexagonal, six to nine times as broad as the bars; twelve to sixteen on the radius. Radial proportion of the three spheres = 1 : 2 : 4. Both medullary shells of the same structure as the cortical shell, only with smaller pores. The three spheres connected by six thin radial beams, which are prolonged on the outside into six strong triangular pyramidal spines, as long as the radius of the cortical shell, and, at the base, as broad as one of its pores. (Differs from Hexastylus phænaxonius and from Hexalonche phænaxonia, Pl. 21, fig. 3, in the larger size and the triple shell.)
Dimensions.—Diameter of the outer sphere 0.2, middle 0.1, inner 0.05; cortical pores 0.008, bars 0.0012; length of the spines 0.1.
Habitat.—Central Pacific, Station 270, surface.
2. Hexacontium axotrias, n. sp. (Pl. 24, fig. 3).
Cortical shell thin walled, smooth; its pores regular circular, five to six times as broad as the bars; eleven to thirteen on the radius. Radial proportion of the three spheres = 1 : 3 : 8. Outer medullary shell with hexagonal frames around the regular circular pores (five to six on the radius). Inner medullary shell with simple small circular pores (three on the radius). The two outer shells connected by six triangular prismatic beams, which are prolonged outside to the length of the cortical radius or more.
Dimensions.—Diameter of the outer sphere 0.2, middle 0.07, inner 0.025; cortical pores 0.016, bars 0.003; length of the spines 0.1 to 0.015, basal breadth 0.02.
Habitat.—North Pacific, Station 253, surface.
3. Hexacontium hexactis, Haeckel.
Actinomma hexactis, Stöhr, 1880, Palæontogr., vol. xxvi. p. 91, Taf. ii. fig. 7.
Cortical shell thick walled, smooth, or a little rough. Pores regular circular, of the same breadth as the bars; five to seven on the radius. Radial proportion of the three spheres = 1 : 3 : 6. Both medullary shells of the same structure, but with smaller pores. Six spines triangular pyramidal, nearly as long as the diameter of the outer shell, three times as broad at the base as one pore.
Dimensions.—Diameter of the outer sphere 0.1, middle 0.05, inner 0.016; cortical pores and bars 0.008; length of the spines 0.08, basal breadth 0.025.
Habitat.—Fossil in Tertiary rocks of Sicily, Grotte, Stöhr.
4. Hexacontium lævigatum, n. sp. (Pl. 24, fig. 6).
Cortical shell thick walled, quite smooth. Pores regular circular, with double margins, eight to ten on the radius, of the same breadth as the smooth bars. Radial proportion of the three spheres = 1 : 2 : 6. All three spheres connected by six very thin radial beams, which are prolonged outside into six short, stout, triangular, pyramidal spines, half as long as the radius of the outer shell.
Dimensions.—Diameter of the outer shell 0.13, middle 0.04, inner 0.02; cortical pores and bars 0.008; length of the spines 0.04, basal breadth 0.02.
Habitat.—South Atlantic, Station 332, depth 2200 fathoms.
5. Hexacontium triplosphærium, n. sp.
Cortical shell thick walled, smooth. Pores regular circular, three times as broad as the bars; ten to twelve on the radius. Radial proportion of the three spheres = 1 : 3 : 10. Six spines conical, about as long as the radius of the cortical shell.
Dimensions.—Diameter of the outer shell 0.16, middle 0.05, inner 0.016; cortical pores 0.012, bars 0.004; length of the spines 0.07, basal breadth 0.02.
Habitat.—Central Pacific, Station 268, depth 2900 fathoms.
6. Hexacontium octahedrum, n. sp.
Cortical shell a regular octahedron, thin walled, with twelve more or less rounded edges (between the spine-bases) and with smooth surface; its pores regular circular, five to seven on the radius, four times as broad as the bars. Radial proportion of the three shells = 1 : 3 : 9. Both medullary shells spherical, with very small circular pores. Six inner bars very thin; six outer spines (their prolongations) triangular pyramidal, as long as the radius of the outer shell. (Differs from Hexalonche octahedra, Pl. 22, fig. 8, almost solely in the duplication of the medullary shell.)
Dimensions.—Diameter of the outer shell 0.12, middle 0.04, inner 0.013.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.
7. Hexacontium circumtextum, n. sp. (Pl. 25, figs. 7, 7a).
Cortical shell double, enclosing a simple medullary shell. Radial proportion of the three spheres = 3 : 10 : 12. Inner cortical shell very thick walled, with regular circular, double-edged pores, four times as broad as the bars; seven to nine on the radius. From each nodal-point between every six pores arises a small, bristle-shaped, radial spine, as long as the diameter of one pore. The distal ends of all these spines are connected by very delicate tangential threads, and consequently form by their attachment an outer cortical shell, with regular hexagonal meshes and smooth surface. Six main spines short, three-sided prismatic, scarcely as long as half the radius of the outer shell.
Dimensions.—Diameter of the outer shell 0.12, middle 0.1, inner 0.03; pores of the middle shell 0.004, bars 0.001; length of the spines 0.025, basal breadth 0.01.
Habitat.—Central Pacific, Station 274, depth 2750 fathoms.
Definition.—Pores of the cortical shell regular or subregular, of nearly equal size and similar form; surface covered with numerous conical or bristle-shaped, radial spines (other than the six main spines).
8. Hexacontium hexagonale, n. sp.
Cortical shell thin walled, bristly, with very delicate network; its pores regular hexagonal, twelve to sixteen on the radius, ten to twelve times as broad as the thin thread-like bars. At each nodal-point of the network (between every three meshes) arises a bristle-shaped, radial spine, as long as the diameter of one mesh. Six main spines hexagonal, as long as the radius of the outer shell, as broad at its base as one mesh. Radial proportion of the three spheres = 1 : 2 : 4. Pores of both medullary shells also regular hexagonal, but much smaller, in the middle shell eleven to twelve, in the inner, six to seven on the half meridian.
Dimensions.—Diameter of the outer shell 0.12, of the middle 0.06, of the inner 0.03; meshes of the outer shell 0.008; length of the six spines 0.05, basal thickness 0.008.
Habitat.—Indian Ocean, Ceylon, surface, Haeckel.
9. Hexacontium favosum, n. sp. (Pl. 24, figs. 2, 2a).
Cortical shell very thick walled, spiny, with regular, honeycomb-like network; its meshes funnel-shaped, with circular inner, hexagonal outer aperture, twice as broad as the bars; five to seven on the radius. Between every three meshes (at each corner of the hexagon) arises a short radial thorn, not so long as the thickness of the shell-wall. Six radial spines very short and stout, three-sided pyramidal, scarcely half so long as the radius of the outer shell. Radial proportion of the three spheres = 1 : 2 : 5. Pores of both medullary shells regular, circular, about as broad as the bars, six to eight on the half meridian.
Dimensions.—Diameter of the outer shell 0.1 to 0.12, of the middle 0.04 to 0.05, of the inner 0.02; meshes of the outer shell 0.008; length of the six spines 0.2 to 0.3, basal breadth 0.015.
Habitat.—Central Pacific, Station 265, depth 2900 fathoms.
10. Hexacontium sceptrum, n. sp. (Pl. 24, figs. 1, 1a).
Cortical shell thick walled, spiny, with regular, honeycomb-like network; its meshes funnel-shaped, with circular inner, hexagonal outer aperture, three to four times as broad as the bars; five to six on the radius. Between every three meshes arises a short radial thorn, as long as the thickness of the shell-wall. Six radial spines sceptre-shaped, six-sided, somewhat constricted towards their middle part, strong, as long as the radius of the outer shell, as broad as one of its meshes. Radial proportion of the three spheres = 1 : 2 : 6. Pores of the two inner shells regular hexagonal, with thin bars, six to eight on the half meridian (fig. 1a).
Dimensions.—Diameter of the outer shell 0.13, of the middle 0.04, of the inner 0.02; pores of the outer shell 0.01, of the middle 0.008, of the inner 0.004; length of the six spines 0.06, basal breadth 0.015.
Habitat.—Equatorial Atlantic, Station 347, surface.
11. Hexacontium prionacanthum, n. sp. (Pl. 24, figs. 7, 7a).
Cortical shell thick walled, thorny; its pores regular circular, with elevated hexagonal frames six to nine on the radius, twice as broad as the crest-shaped bars. At each nodal-point of the hexagon arises one short conical papilla or thorn. Radial proportion of the three spheres = 1 : 3 : 10. Pores of both medullary shells much smaller, regular circular. Six main spines three-sided prismatic, longer than the radius of the outer shell, as broad as one of its meshes; their three edges serrated, with ten to twelve teeth.
Dimensions.—Diameter of the outer shell 0.15, middle 0.045, inner 0.015; cortical pores 0.01, bars 0.005; length of the spines 0.1, breadth 0.012.
Habitat.—West Tropical Pacific, Station 225, depth 4475 fathoms.
12. Hexacontium clavigerum, n. sp. (Pl. 23, fig. 5).
Cortical shell very thick walled, thorny; its pores regular circular, hexagonally framed, three times as broad as the bars, nine to twelve on the radius; between them short conical papillæ or thorns arising at the nodal-points. Radial proportion of the three spheres = 1 : 2 : 5. Outer medullary shell with regular circular, much smaller pores; connected with the cortical shell by numerous (twenty to thirty) thin radial beams. Six main spines very stout, club-shaped, scarcely as long as the radius of the outer shell, three times as broad as one of its pores, three-sided, with three to four teeth on each edge.
Dimensions.—Diameter of the outer shell 0.2, of the middle 0.08, of the inner 0.04; cortical pores 0.012, bars 0.004; length of the six spines 0.08, breadth 0.03.
Habitat.—South Atlantic, Station 332, depth 2200 fathoms.
13. Hexacontium floridum, n. sp. (Pl. 24, fig. 4).
Cortical shell papillose, thick walled. Pores regular, six-lobed, four times as broad as the bars, five to seven on the radius; each pore with six (sometimes also five or seven) concave indentations or lobules; between the pores at the nodal-points arise short conical papillæ or thorns. Radial proportion of the three spheres = 1 : 2 : 3. Radial main spines pommel-shaped, three-sided prismatic, longer than the radius of the outer shell, two to three times as broad as one pore.