Legion I. SPUMELLARIA, (continued 5)

Habitat.—Indian Ocean, Zanzibar, Pullen; Madagascar, Rabbe.

14. Hexastylus chilonis, n. sp.

Shell thin walled, covered with numerous bristle-shaped spines (as long as the radius). Pores regular, circular, twice as broad as the bars; eight to nine on the radius. Six main spines triangular pyramidal, with straight edges, as long as the diameter of the shell, as broad as two pores.

Dimensions.—Diameter of the shell 0.2, pores 0.02, bars 0.01; length of the spines 0.2, basal breadth 0.05.

Habitat.—South Atlantic, Station 325, surface.

15. Hexastylus cleobuli, n. sp.

Shell thick walled, covered with numerous short, conical spines (twice as large as one pore). Pores regular, circular, of the same breadth as the bars; twelve to thirteen on the radius. Six main spines conical, as long as the radius, three times as broad as one pore.

Dimensions.—Diameter of the shell 0.24, pores and bars 0.005; length of the spines 0.12, basal breadth 0.016.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

Subgenus 3. Hexastylissus, Haeckel.

Definition.—Pores irregular, of unequal size or form; surface of the spherical shell smooth, without radial by-spines (other than the six main spines).

16. Hexastylus triaxonius, n. sp. (Pl. 21, fig. 2).

Shell thin walled, with smooth surface. Pores irregular, polygonal, three to six times as broad as the bars; four to six on the radius. Six spines triangular pyramidal, as long as the diameter of the shell, as broad at the base as one pore.

Dimensions.—Diameter of the shell 0.05, pores 0.004 to 0.008, bars 0.0015; length of the spines 0.04, basal breadth 0.006.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

17. Hexastylus dimensivus, n. sp. (Pl. 21, fig. 6).

Shell thin walled, with smooth surface. Pores irregular, polygonal, four to eight times as broad as the bars; eleven to thirteen on the radius. Six spines hexagonal pyramidal, as long as the radius, about three times as broad at the base as one pore.

Dimensions.—Diameter of the shell 0.13, pores 0.006 to 0.009, bars 0.0012; length of the spines 0.06, basal breadth 0.025.

Habitat.—North Pacific, Station 256, depth 2950 fathoms.

18. Hexastylus brevispinus, n. sp.

Shell thin walled, with smooth surface. Pores irregular, roundish, two to four times as broad as the bars; six to eight on the radius. Six spines triangular pyramidal, half as long as the radius, twice as broad as one pore.

Dimensions.—Diameter of the shell 0.2, pores 0.008 to 0.016, bars 0.004; length of the spines 0.05, basal breadth 0.025.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

19. Hexastylus longispinus, n. sp.

Shell thick walled, smooth. Pores irregular, roundish, two to three times as broad as the bars; three to four on the radius. Six spines triangular prismatical, two to three times as long as the diameter of the shell.

Dimensions.—Diameter of the shell 0.08, pores 0.008 to 0.012, bars 0.004; length of the spines 0.2, breadth 0.01.

Habitat.—North Atlantic, Station 353, surface.

20. Hexastylus marginatus, n. sp. (Pl. 21, fig. 10).

Shell thick walled, rough. Pores irregular, roundish, somewhat funnel-shaped double-edged, two to three times as broad as the bars; twelve to fourteen on the radius. Six spines three-sided pyramidal, somewhat longer than the radius, three times as broad as one pore.

Dimensions.—Diameter of the shell 0.15, pores 0.007 to 0.01, bars 0.004; length of the spines 0.1, basal breadth 0.025.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

21. Hexastylus conifer, n. sp.

Shell thick walled, rough. Pores irregular, roundish, scarcely broader than the bars; fifteen to sixteen on the radius. Six spines conical, as long as the radius, five to seven times as broad as one pore.

Dimensions.—Diameter of the shell 0.18, pores and bars 0.004 to 0.006; length of the spines 0.1, basal breadth 0.03.

Habitat.—Indian Ocean, Sunda Strait, Rabbe, surface.

Subgenus 4. Hexastylurus, Haeckel.

Definition.—Pores irregular, of unequal size or form; surface of the spherical shell spiny, covered with numerous conical or bristle-shaped by-spines.

22. Hexastylus dictyotus, n. sp. (Pl. 21, figs. 8, 9).

Shell thin walled, spiny; short spines conical, smaller than the pore-breadth. Pores irregular, polygonal, five to seven times as broad as the bars; four to six on the radius. Six spines triangular pyramidal, longer than the radius, about as broad as one smaller pore.

Dimensions.—Diameter of the shell 0.09, pores 0.01 to 0.015, bars 0.002; length of the spines 0.06, basal breadth 0.01.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

23. Hexastylus hirsutus, n. sp.

Shell thin walled, densely covered with bristle-shaped, radial spines, half as long as the six main spines. Pores irregular, polygonal, three to four times as broad as the bars; eight to ten on the radius. Six spines triangular pyramidal, as long as the radius, twice as broad as one pore.

Dimensions.—Diameter of the shell 0.14, pores 0.005 to 0.008, bars 0.002; length of the spines 0.06, basal breadth 0.01.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

24. Hexastylus contortus, n. sp. (Pl. 21, fig. 12).

Shell thick walled, covered with bristle-shaped, radial spines, half as long as the radius. Pores irregular, roundish, two to three times as broad as the bars; seven to eight on the radius. Six spines triangular prismatic, in the distal half spirally twisted like a cork-screw (fig. 12); longer than the diameter of the shell, about as broad as one pore.

Dimensions.—Diameter of the shell 0.12, pores 0.006 to 0.008, bars 0.003; length of the spines 0.15, breadth 0.015.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

25. Hexastylus spiralis, n. sp. (Pl. 21, fig. 7).

Shell thick walled, covered with short conical spines. Pores irregular, roundish, two to three times as broad as the bars; five to six on the radius. Six spines triangular prismatic, with three thin, spirally contorted edges, two to three times as long as the diameter of the shell, about as broad as one large pore.

Dimensions.—Diameter of the shell 0.16, pores 0.01 to 0.02, bars 0.006; length of the spines 0.3 to 0.5, basal breadth 0.02.

Habitat.—Tropical Western Pacific, Station 225, depth 4475 fathoms.

Genus 73. Hexastylarium,^[102] n. gen.

Definition.—Cubosphærida with one simple lattice-sphere and six simple spines of different sizes; one opposite pair larger than the other two.

The genus Hexastylarium differs from its probable ancestral form, Hexastylus, by the unequal growth of the six simple spines; two opposite spines of one pair being more strongly developed than the four others, which are equal. They correspond therefore to the three axes of a quadratic crystal.

1. Hexastylarium heteraxonium, n. sp.

Cortical shell thin walled, smooth, with regular, hexagonal pores, three times as broad as the bars; eight to ten on the radius. Six spines three-sided pyramidal, at the base as broad as one pore. Two opposite major spines longer than the shell diameter; four others scarcely as long as the radius. (Similar to Hexastylus phænaxonius, Pl. 21, fig. 3, but differing in the unequal length of the spines.)

Dimensions.—Diameter of the shell 0.15, pores 0.12, bars 0.004; length of the two major spines 0.2, of the four minor 0.07.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

2. Hexastylarium quadratum, n. sp.

Shell very delicate, with smooth surface, and irregular, polygonal pores, separated by very thin bars. The form of the shell is not, as commonly, a sphere, but a geometrical square octahedron, one axis (with two opposite major spines) being nearly twice as long as the other two dimensive axes; four spines, opposite by pairs in the latter, are only half as long. The eight sides of the octahedral shell are even, equilateral-triangular. Spines angular, thin.

Dimensions.—Diameter of the shell in the major axis 0.18, in the minor 0.1; length of the major spines 0.24, minor 0.12.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

3. Hexastylarium elongatum, n. sp.

Shell thick walled, with spiny surface, and with irregular, roundish pores, two to four times as broad as the bars; eight to ten on the radius. Two opposite major spines, three to four times as long as the shell diameter, whilst the four other spines are very short, scarcely as long as the radius. All six spines at the base three-sided pyramidal, the two longer being cylindrical.

Dimensions.—Diameter of the shell 0.1; length of the major spines 0.3 to 0.4, of the minor 0.04, basal breadth 0.02.

Habitat.—North Pacific, Station 244, surface.

Genus 74. Hexastylidium,^[103] Haeckel, 1881, Prodromus, p. 450.

Definition.—Cubosphærida with one simple lattice-sphere and six simple spines in pairs different; the two opposite spines of each pair equal, the three pairs unequal.

The genus Hexastylidium differs from its probable ancestral form, Hexastylus, by the unequal growth of the six simple spines; the two spines of each pair reaching the same dimensions, whilst the three pairs are different. They correspond therefore to the three axes of a rhombic crystal.

1. Hexastylidium rhomboides, n. sp.

Shell thin walled, smooth, with irregular, polygonal pores and very thin bars. Its form is not, as commonly, a sphere, but a rhombic octahedron. The radial proportion of the three unequal dimensive axes = 1 : 2 : 4. The radial proportion of the three pairs of spines = 1 : 3 : 8. Spines thin cylindrical, at the base angular.

Dimensions.—Diameter of the major shell axis 0.2, middle 0.1, minor 0.05; length of the major spines 0.3, middle 0.12, minor 0.04.

Habitat.—Indian Ocean, Madagascar, Rabbe, surface.

2. Hexastylidium spirale, n. sp.

Shell thick walled, spherical, thorny, with irregular, roundish pores, three to five times as broad as the bars; six spines very stout, prismatic (as broad as one large pore), with three ring-like, spirally convoluted edges. Two opposite major spines of extraordinary length, ten to twelve times as long as the shell diameter, the two middle opposite spines being about as long as the latter, the two minor scarcely one-third as long. (Similar to Hexastylus spiralis, Pl. 21, fig. 7, but distinguished by the very unequal length of the spines.)

Dimensions.—Diameter of the shell 0.12; length of the major spines 1 to 1.5 mm., middle 0.15, minor 0.04.

Habitat.—Central Pacific, Station 266, surface.

Subfamily Hexalonchida,^[104] Haeckel, 1881, Prodromus, pp. 449, 451.

Definition.—Cubosphærida with two concentric spherical lattice-shells.

Genus 75. Hexalonche,^[105] Haeckel, 1881, Prodromus, p. 451.

Definition.—Cubosphærida with two concentric lattice-spheres and six simple spines of equal size.

The genus Hexalonche is the most simple form, and probably the common ancestral form, of all Hexalonchida, or those Cubosphærida which possess two concentric latticed spheres, connected by six radial beams. Commonly one shell is intracapsular (medullary shell) and the other extracapsular (cortical shell); but sometimes also both shells are extracapsular, and these forms may perhaps be better separated as a peculiar genus Hexadilemma. In Hexalonche all six simple spines are of equal size, and opposite by pairs in three equal dimensive axes, corresponding to the three equal axes of a tesseral crystal. It can be derived from Hexastylus by duplication of the lattice-shell.

Subgenus 1. Hexalonchara, Haeckel.

Definition.—Pores of the cortical shell regular or subregular, of nearly equal size and similar form; surface smooth, without radial by-spines (other than the six main spines).

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.

Subgenus 2. Hexalonchetta, Haeckel.

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.

Subgenus 3. Hexalonchilla, Haeckel.

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.

Subgenus 4. Hexalonchusa, Haeckel.

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.

Genus 76. Hexancistra,^[106] Haeckel, 1881, Prodromus, p. 451.

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.

Subgenus 1. Hexancora, Haeckel.

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.

Subgenus 2. Hexapitys, Haeckel, 1881, Prodromus, p. 451.

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.

Genus 77. Hexaloncharium,^[107] n. gen.

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.

Genus 78. Hexalonchidium,^[108] Haeckel, 1881, Prodromus, p. 451.

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.

Subfamily Hexacontida,^[109] Haeckel, 1881, Prodromus, pp. 449, 452.

Definition.—Cubosphærida with three concentric, spherical, or octahedral lattice-shells.

Genus 79. Hexacontium, Haeckel,^[110] 1881, Prodromus, p. 452.

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.

Subgenus 1. Hexacontanna, Haeckel.

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.

Subgenus 2. Hexacontella, Haeckel.

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.

Dimensions.—Diameter of the outer shell 0.12, middle 0.06, inner 0.03; cortical pores 0.012, bars 0.003; length of the six spines 0.08, breadth 0.03.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

14. Hexacontium hexaconicum, n. sp.

Cortical shell spiny, thick walled. Pores regular circular, of the same breadth as the bars, ten to twelve on the radius; between them long bristle-shaped by-spines, half as long as the six main spines. Radial proportion of the three spheres = 1 : 3 : 9. Six main spines conical, as long as the radius of the outer shell, four times as broad at the base as one pore.

Dimensions.—Diameter of the outer shell 0.18, middle 0.06, inner 0.02; cortical pores and bars 0.005; length of the spines 0.1, basal breadth 0.02.

Habitat.—Antarctic Sea, Station 157, depth 1950 fathoms.

15. Hexacontium asteracanthion, Haeckel.

Haliomma asteracanthion, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 816.

Actinomma asteracanthion, Haeckel, 1862, Monogr. d. Radiol., p. 441, Taf. xxiii. figs. 5, 6.

Cortical shell thin walled, spiny; its pores circular, without hexagonal frame (as a rule very regular, but in other specimens more or less irregular), often very variable in size, three to six times as broad as the bars, commonly seven to eight on the radius. Radial proportion of the three spheres = 1 : 2 : 4, or sometimes 1 : 3 : 8. Pores of the two inner shells also circular, but much smaller; those of the middle shell about half as broad, those of the inner shell one-fourth to one-sixth as broad as the pores of the outer shell. Six radial spines strong, three-sided prismatic, about as long as (or somewhat longer than) the radius of the outer shell, as broad as one of its large meshes. Accessory spines very numerous and very thin, bristle-like, usually half as long as the six main spines. (For the variability of this common species compare my Monograph, p. 442.)

Dimensions.—Diameter of the outer shell 0.1 to 0.12, of the middle 0.04 to 0.06, of the inner 0.02 to 0.03; cortical pores 0.005 to 0.01; length of the six spines 0.06 to 0.08.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.

Subgenus 3. Hexacontosa, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form; surface smooth, without radial by-spines or papillæ (other than the six main spines).

16. Hexacontium axophænum, n. sp.

Cortical shell thin walled, smooth. Pores irregular polygonal, three to nine times as broad as the bars; seven to ten on the radius. Radial proportion of the three spheres = 1 : 3 : 8. Both medullary shells with smaller, irregular roundish pores. Six spines three-sided pyramidal, longer than the radius of the outer shell, one to two times as broad as one larger pore.

Dimensions.—Diameter of the outer shell 0.12, middle 0.045, inner 0.015; cortical pores 0.006 to 0.018, bars 0.002; length of the spines 0.06 to 0.12, basal breadth 0.02 to 0.03.

Habitat.—Central Pacific, Stations 266 to 272, at various depths.

17. Hexacontium polygonale, n. sp.

Cortical shell thick walled, smooth. Pores irregular roundish, with polygonal frames, two to four times as broad as the bars; eight to twelve on the radius. Radial proportion of the three spheres = 1 : 3 : 10. Six spines pyramidal, nearly as long as the diameter of the outer shell, with six to nine prominent edges (along the corner number of the polygonal meshes).

Dimensions.—Diameter of the outer shell 0.2, middle 0.06, inner 0.02; cortical pores 0.008 to 0.016, bars 0.004; length of the spines 0.16 to 0.18, basal breadth 0.02.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

18. Hexacontium antarcticum, n. sp.

Cortical shell thin walled, smooth, with irregular roundish pores, eight to ten on the radius, two to four times as broad as the bars. Radial proportion of the three spheres = 1 : 3 : 9. Both medullary shells with smaller roundish irregular pores. Six spines conical, pyramidal at their origin, about as long as the radius, as broad as one larger mesh.

Dimensions.—Diameter of the outer shell 0.18, middle 0.06, inner 0.02; cortical pores 0.006 to 0.012, bars 0.003; length of the spines 0.1, basal breadth 0.12.

Habitat.—Antarctic Ocean, Station 157, depth 1950 fathoms.

Subgenus 4. Hexacontura, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form; surface covered with numerous conical papillæ or bristle-shaped, radial by-spines (other than the six main spines).

19. Hexacontium papillosum, n. sp. (Pl. 24, fig. 5).

Cortical shell thick walled, papillose. Pores irregular roundish, often somewhat lobed, five to six on the radius, two to four times as broad as the bars. Radial proportion of the three spheres = 1 : 2.5 : 5. Both medullary shells with subregular circular pores (inner much smaller). Six radial spines short and stout, pommel or club shaped, with three prominent wings, about as long as the shell radius, and as broad as the medullary shell.

Dimensions.—Diameter of the outer shell 0.1, middle 0.05, inner 0.02, cortical pores 0.006 to 0.012, bars 0.003; length of the spines 0.05, bars 0.02.

Habitat.—Central Pacific, Stations 266 to 272, at various depths.

20. Hexacontium gladiatum, n. sp. (Pl. 25, fig. 8).

Cortical shell very thick walled, spiny, with irregular network; its meshes roundish, two to five times as broad as the bars, of very different size, ten to fifteen on the half meridian. Bars between them very strong, three-sided prismatic, armed with a great number of small thorns, and with large spines at the nodal-points between every three meshes. Radial proportion of the three spheres = 1 : 3 : 12. Six strong radial main spines three-sided prismatic, with three prominent, somewhat contorted wings, acute, broader than the diameter of the inner shell and as long as the diameter of the outer shell. These six main spines are situated in the same three dimensive axes as the six thin radial beams connecting the two medullary shells. But the six radial beams which connect the middle with the outer shell alternate with the former and lie in three other dimensive axes,—a very rare and remarkable disposition.

Dimensions.—Diameter of the outer shell 0.2, middle 0.05, inner 0.016; cortical pores 0.01 to 0.03, bars 0.006; length of the six spines 0.2, breadth 0.02 to 0.03.

Habitat.—Tropical Atlantic, Station 342, depth 1445 fathoms.

21. Hexacontium setosum, n. sp.

Cortical shell thin walled, with numerous bristle-shaped, simple, radial by-spines of variable length. Pores irregular roundish, five to seven on the radius, two to eight times as broad as the bars. Radial proportion of the three spheres = 1 : 3 : 9. Main spines three-sided pyramidal, as long as the radius.

Dimensions.—Diameter of the outer shell 0.1 to 0.015, middle 0.035 to 0.05, inner 0.013 to 0.016; cortical pores 0.01 to 0.03, bars 0.003 to 0.004; length of the six spines 0.05 to 0.08, basal breadth 0.012 to 0.015.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific, surface; also fossil in Barbados.

22. Hexacontium furcatum, n. sp.

Cortical shell thin walled, covered with numerous thin, bristle-shaped by-spines, which are forked and nearly as long as the main spines. Pores irregular roundish, eight to ten on the radius, two to eight times as broad as the bars. Radial proportion of the three spheres = 1 : 2.5 : 10. Main spines triangular pyramidal, shorter then the radius.

Dimensions.—Diameter of the outer shell 0.18, middle 0.045, inner 0.018; cortical pores 0.005 to 0.015, bars 0.002; length of the six spines 0.07, basal breadth 0.015.

Habitat.—North Atlantic, Station 354, surface.

23. Hexacontium drymodes, Haeckel.

Actinomma drymodes, Haeckel, 1862, Monogr. d. Radiol., p. 442, Taf. xxiv. fig. 9.

Cortical shell thin walled, covered with numerous thin, bristle-shaped spines, which are double forked and half as long as the main spines. Pores irregular roundish, eight to ten on the radius, two to eight times as broad as the bars. Radial proportion of the three spheres = 1 : 2 : 4. Main spines three-sided prismatic, with prominent, often somewhat contorted edges, at the distal end cuspidated; longer than the radius of the outer shell.

Dimensions.—Diameter of the outer shell 0.15, middle 0.07, inner 0.035; cortical pores 0.01 to 0.03, bars 0.04; length of the six spines 0.11, basal breadth 0.03.

Habitat.—Mediterranean (Messina), surface; Canary Islands (Lanzerote); Haeckel.

24. Hexacontium periplectum, n. sp.

Cortical shell double, enclosing a simple medullary shell. Radial proportion of the three shells = 1 : 4 : 5. Inner cortical shell thick walled, with irregular roundish pores, two to eight times as broad as the bars; five to seven on the radius. Numerous radial spines, arising from it, are connected below their distal ends (at equal distances from the centre) by delicate branched threads, and so form an outer, irregular, thin, cortical shell, with spiny surface. Six main spines three-sided pyramidal, about as long as the radius.

Dimensions.—Diameter of the outer shell 0.22, middle 0.2, inner 0.045; cortical pores (of both outer shells) 0.01 to 0.03, bars 0.001 to 0.005; length of the spines 0.1, basal breadth 0.02.

Habitat.—North Pacific, Station 241, surface.

Genus 80. Hexadendron,^[111] Haeckel, 1881, Prodromus, p. 452.

Definition.—Cubosphærida with three concentric lattice-spheres and six branched spines of equal size.

The genus Hexadendron differs from Hexacontium in the ramification of the six dimensive spines, and from the similar Hexancistra in the duplication of the medullary shell. As in the latter instance, each spine can bear either three simple lateral branches or three rows of pinnate lateral branches.

1. Hexadendron quadricuspis, n. sp.

All three shells spherical, with radial proportion = 1 : 2 : 6. Pores of both medullary shells regular circular, twice as broad as the bars. Pores of the cortical shell irregular roundish, four to six times as broad as the bars; surface a little thorny. Six radial spines prismatic, with three prominent wing-like edges, which are prolonged below the distal end in three curved lateral branches. (Differs from Hexalonche quadricuspis, Pl. 22, fig. 11, mainly in the double medullary shell.)

Dimensions.—Diameter of the outer shell 0.15, middle 0.05, inner 0.025; length of the spines 0.12, breadth 0.01.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Hexadendron bipinnatum, n. sp. (Pl. 23, fig. 1).

All three shells regular octahedral, with very delicate network of irregular polygonal meshes, and very thin, thread-like bars between them; their radial proportion = 1 : 2.5 : 7.5. Surface of the cortical shell covered with numerous bristle-shaped by-spines, as long as the radius. Six main spines very large, three-sided prismatic, with three rows of pinnate, lateral branches, on the three wing-like, spirally twisted edges (similar to those of Hexancistra mirabilis, p. 189, Pl. 23, fig. 3).

Dimensions.—Diameter of the outer shell 0.12, middle 0.04, inner 0.016.

Habitat.—Central Pacific, Station 272, surface.

Genus 81. Hexacontarium,^[112] n. gen.

Definition.—Cubosphærida with three concentric lattice-spheres and six simple spines of different size; one opposite pair larger than the two others.

The genus Hexacontarium exhibits to its ancestral form Hexacontium the same relation that Hexaloncharium bears to Hexalonche; the former is developed from the latter by duplication of the medullary shell. As two opposite spines of one pair are larger than the four others, they correspond to the three axes of a quadratic crystal.

1. Hexacontarium dentatum, n. sp.

Cortical shell with regular circular, hexagonally framed pores, twice as broad as the bars, with smooth surface. Radial proportion of the three spheres = 1 : 2 : 5. Six radial spines three-sided prismatic, half as broad as the inner medullary shell, with three dentated edges. Two opposite major spines longer than the shell diameter; four other minor spines only half as long as the radius. (Similar to Hexacontium clavigerum, Pl. 23, fig. 5, but distinct by the prolongation of the spines of one axis.)

Dimensions.—Diameter of the outer shell 0.15, middle 0.06, inner 0.03; length of the major spines 0.2, minor 0.04.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Hexacontarium clavatum, n. sp.

Cortical shell covered with short conical by-spines and irregular roundish pores, three to four times as broad as the bars. Radial proportion of the three spheres = 1 : 3 : 8. Six radial spines three-sided prismatic, at the distal end club-shaped; two major spines three times as long as the four others, which are equal to the shell radius.

Dimensions.—Diameter of the outer shell 0.16, middle 0.06, inner 0.02.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Subfamily Hexacromyida,^[113] Haeckel, 1881, Prodromus, pp. 449, 453.

Definition.—Cubosphærida with four concentric spherical lattice-shells.

Genus 82. Hexacromyum,^[114] Haeckel, 1881, Prodromus, p. 453.

Definition.—Cubosphærida with four concentric lattice-spheres and six simple spines of equal size.

The genus Hexacromyum possesses four concentric, spherical, or octahedral lattice-shells; two inner medullary shells within the central capsule, two outer cortical outside it. The four spheres are connected by six radial beams, which are prolonged outside into simple spines of equal size, opposite in pairs in the three dimensive axes. This genus can be derived from Hexacontium by duplication of the cortical shell.

1. Hexacromyum elegans, n. sp. (Pl. 24, fig. 9).

Shell composed of four concentric shells, with radial proportion = 1 : 2.5 : 7.5 : 10. First (innermost) shell with very small circular pores, second shell with larger circular pores. Third shell (inner cortical shell) with large, subregular, circular, hexagonally framed pores (eight to nine on the radius), twice as broad as the bars; from the elevated nodal-points of the hexagonal frames (between every three pores) arise thin bristle-shaped radial beams, which are united at the distal end by vaulted branches forming the delicate fourth shell. Surface smooth. Radial spines three-sided pyramidal, as long as the radius, as broad at the base as the innermost shell.

Dimensions.—Diameter of the four shells—(A) 0.02, (B) 0.05, (C) 0.15, (D) 0.2; length of the six radial spines 0.1, basal breadth 0.02.

Habitat.—Central Pacific, Station 271, surface.

2. Hexacromyum quadrigatum, n. sp.

Shell composed of four concentric shells, with radial proportion = 1 : 3 : 8 : 10. Structure of all four shells the same, with regular, circular pores, twice to three times as broad as the bars; size of the pores gradually increasing from the innermost to the outermost shell; surface smooth. Radial spines three-sided pyramidal, as long as the radius, half as broad at the base as the innermost shell.

Dimensions.—Diameter of the four shells—(A) 0.025, (B) 0.08, (C) 0.20, (D) 0.25; length of the spines 0.12, basal breadth 0.012.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

3. Hexacromyum arachnoides, n. sp.

Hexacromidium arachnoides, Haeckel, 1881, Prodromus, p. 453.

Shell composed of four concentric shells, with radial proportion = 1 : 2 : 3 : 4. Innermost shell with regular, hexagonal meshes; the three other shells with irregular, polygonal meshes; bars between the large meshes in all four shells very thin, cobweb-like. Surface covered with thin bristle-shaped by-spines, as long as the radius. Six radial main spines three-sided prismatic, longer than the diameter of the whole shell.

Dimensions.—Diameter of the four shells—(A) 0.08, (B) 0.16, (C) 0.24, (D) 0.32; length of the spines 0.4, breadth 0.01.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

4. Hexacromyum octahedrum, n. sp. (Pl. 23, fig. 2).

Shell composed of four concentric shells which are not spherical (as in the three preceding species), but regular octahedral. Radial proportion = 1 : 2.5 : 6 : 9. Network in all four shells delicate, with irregular polygonal meshes and thin bars; the thickness of the bars and size of the meshes increasing from the innermost to the outermost shell. Six radial spines three-sided prismatic, increasing slowly in breadth towards the distal end, much longer than the shell diameter.

Dimensions.—Diameter of the four shells—(A) 0.02, (B) 0.05, (C) 0.12, (D) 0.18; length of the radial spines 0.2 to 0.3 and more, breadth 0.01.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms.

Subfamily Hexacaryida,^[115] Haeckel, 1881, Prodromus, p. 454.

Definition.—Cubosphærida with five or more concentric lattice-shells.

Genus 83. Cubosphæra,^[116] n. gen.

Definition.—Cubosphærida with five to six or more concentric lattice-shells and six simple spines of equal size.

The genus Cubosphæra is developed from the preceding Hexacromyum by further addition of the concentric lattice-shells, their number amounting to five, six, or more. The innermost two of these are medullary shells, the others being cortical shells. All are connected by six radial beams, prolonged outside into six simple spines of equal size; these lie opposite in pairs in three dimensive axes, corresponding to the three axes of a cube.

1. Cubosphæra cubaxonia, n. sp. (Pl. 24, fig. 8).

Hexacromyon cubaxonium, Haeckel, 1881, Prodrom. et Atlas.

Shell composed of five concentric spheres, with the radial proportion = 1 : 3 : 8 : 10 : 13. The two medullary shells with small regular, circular pores of the same breadth as the bars. Inner cortical shell (third shell) with large regular, circular pores, four times as broad as the bars, hexagonally framed. From each hexagon-corner arises a thin bristle-shaped radial by-spine, which at a fixed distance from the centre is united with the middle cortical shell (fourth shell), which has very small circular pores. The beginning of the fifth shell (outermost) is indicated by six small reticula, produced by the six main spines at equal distances from the centre. All five shells are united by six prismatic radial beams, ending outside in pyramidal furrowed spines.

Dimensions.—Diameter of the five shells—(A) 0.2, (B) 0.15, (C) 0.12, (D) 0.045, (E) 0.015.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Cubosphæra concentrica, n. sp.

Shell composed of six concentric spheres, with the radial proportion = 1 : 2 : 6 : 7.5 : 9 : 11. The two medullary shells with regular, circular pores, twice as broad as the bars. The four cortical shells of the same structure, with irregular, roundish pores, three to four times as broad as the bars. The size of these pores and the breadth of their bars gradually increase towards the smooth surface. All six shells are connected by six thin three-sided prismatic radial beams, which are prolonged outside in six stronger spines, angular pyramidal, with smooth edges, as long as the shell radius.

Dimensions.—Diameter of the six shells—(A) 0.02 (B) 0.04, (C) 0.12, (D) 0.15, (E) 0.18, (F) 0.22.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Genus 84. Hexacaryum,^[117] Haeckel, 1881, Prodromus, p. 454.

Definition.—Cubosphærida with five to six or more concentric lattice-shells and six branched spines of equal size.

The genus Hexacaryum is distinguished from the foregoing Cubosphæra by ramification of the six radial spines, and therefore exhibits the same relation to it that Hexancistra bears to Hexastylus, &c.

1. Hexacaryum arborescens, n. sp. (Pl. 23, figs. 4, 4a).

Shell composed of five, six, or more concentric shells, which are united by six very large radial spines. The two medullary shells spherical, inner with regular, circular, outer with irregular polygonal pores. All cortical shells (third and following) not spherical, but regular octahedral, with irregular polygonal meshes and thin bars. Radial spines prismatic, with three wing-like, spirally twisted edges, which at equal distances send out thin forked lateral branches (six on each verticil); by further ramification and communication of these branches the triangular net-plates arise, filling out the sides of the octahedral cortical shells. Diameter of all shells little different. The outer free parts of the six spines are arborescent, twice to three times as long as the enclosed inner parts, and bear six to eight verticils of free lateral branches, decreasing in size towards the distal end (similar to Arachnosphæra).

Dimensions.—Diameter of the six shells—(A) 0.015, (B) 0.04, (C) 0.1, (D) 0.16, (E) 0.22, (F) &c.; average distance of the concentric octahedra = 0.06; length of the radial spines 0.3 to 0.4 and more, breadth 0.02.

Habitat.—Central Pacific, Station 274, surface.

Subfamily Hexadorida,^[118] Haeckel, 1881, Prodromus, pp. 449, 455.

Definition.—Cubosphærida with spongy spherical or octahedral shell (with or without enclosed concentrical lattice-shells).

Genus 85. Cubaxonium,^[119] n. gen.

Definition.—Cubosphærida with solid spongy spherical or octahedral shell, without latticed medullary shell in the centre, and with six simple radial spines of equal size.

The genus Cubosphæra may be regarded as a form of Styptosphæra, which develops six radial spines, opposite in pairs in the three dimensive axes. The solid spongy framework of the shell assumes the outer form either of a sphere, or of a regular octahedron.

1. Cubaxonium spongiosum, n. sp.

Spongy shell spherical, composed of a very dense spongy framework of nearly uniform structure; the meshes three to four times as broad as the bars; surface almost smooth. Six spines cylindrical, twice to three times as long as the diameter of the spongy sphere, about as broad as one half mesh.

Dimensions.—Diameter of the sphere 0.2, meshes 0.006 to 0.008, bars 0.002; length of the spines 0.4 to 0.5, breadth 0.004.

Habitat.—South Pacific, Station 288, surface.

2. Cubaxonium octahedrum, n. sp.

Spongy shell octahedral, composed of a loose spongy framework of nearly uniform structure; the meshes ten to twelve times as broad as the bars; surface thorny. Six spines three-sided pyramidal, longer than the diameter of the octahedron, arising from its six corners, as broad at the base as one mesh.

Dimensions.—Diameter of the shell 0.15, meshes 0.01 to 0.012, bars 0.001; length of the spines 0.2, basal breadth 0.01.

Habitat.—South Pacific, Station 300, surface.

Genus 86. Hexadoras,^[120] Haeckel, 1881, Prodromus, p. 455.

Definition.—Cubosphærida with spongy spherical shell and one simple latticed medullary shell in its centre, having six simple spines of equal size.

The genus Hexadoras exhibits the same structure of the spongy shell as Spongoplegma, but differs from it in the production of six dimensive spines. In the centre lies one simple, latticed, medullary shell, which is either spherical or octahedral. In the latter case the six spines arise from the six corners of the octahedron.

1. Hexadoras axophæna, n. sp.

Medullary shell spherical, with regular hexagonal meshes, twice as broad as the bars. Cortical shell entirely enclosing it, with loose irregular framework and thorny surface. Diameter of the outer shell three times as large as that of the inner. Six radial spines arising from the medullary shell, four to five times as long as the radius of the cortical shell, three-sided prismatic, with straight dentated edges.

Dimensions.—Diameter of the outer shell 0.15, inner 0.05; length of the spines 0.3 to 0.4.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

2. Hexadoras lychnosphæra, n. sp.

Medullary shell spherical, with regular, circular, hexagonally framed pores, three times as broad as the bars. Cortical shell enveloping it, with loose irregular framework and spiny surface. Diameter of the outer shell eight times as large as that of the inner. Six radial spines arising from the inner shell, three-sided prismatic, with dentated, spirally contorted edges, seven times as long as the diameter of the medullary shell, with three lateral branches at the distal end (similar to Lychnosphæra, Pl. 11, fig. 1).

Dimensions.—Diameter of the outer shell 0.5, inner 0.06; total length of the spines 0.4, breadth 0.01.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

3. Hexadoras octahedrum, n. sp.

Medullary shell regular octahedral, with irregular polygonal meshes, five times as broad as the bars. Cortical shell enveloping it, with dense spongy framework, also octahedral with rough surface. Diameter of the outer shell five times as large as that of the inner. Six radial spines very long, arising from the six corners of the inner and piercing the spongy mass of the outer shell, considerably exceeding it at the free distal end, three-sided prismatic, with elegantly denticulate edges.

Dimensions.—Diameter of the outer shell 0.2, inner 0.04; total length of the spines 0.3 or more, breadth 0.02.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Genus 87. Hexadoridium,^[121] Haeckel, 1881, Prodromus, p. 455.

Definition.—Cubosphærida with spongy spherical shell and two concentric latticed medullary shells in its centre, having six simple spines of equal size.

The genus Hexadoridium differs from Hexadoras in the duplication of the medullary shell, and exhibits therefore the same relation to it that Spongodictyon bears to Spongoplegma. In the only known species the six spines are opposite, arranged quite regularly in pairs in the three dimensive axes, and consequently represent the three axes of a regular crystal or cube.

1. Hexadoridium streptacanthum, n. sp. (Pl. 25, figs. 1, 1a).

Both medullary shells spherical, with small regular, circular pores, twice as broad as the bars; outer twice as broad as the inner. Spongy cortical shell enclosing it with dense framework, five times as broad as the outer medullary shell, regular octahedral. Six radial spines, arising from the latter, are thinned at the inner end, three to five times as long as the diameter of the cortical shell, and nearly as broad as the inner medullary shell, with three dentated and spirally contorted edges. (Very similar to the common Spongosphæra streptacantha, with irregular and variable number and dispositions of spines; possibly its ancestral form?).

Dimensions.—Diameter of the cortical shell 0.2, of the outer medullary shell 0.04, inner 0.02; length of the spines 1 mm. and more, breadth 0.02.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Family X. Astrosphærida (Pls. 11, 18-20, 26-30).

Astrosphærida, Haeckel, 1881, Prodromus, p. 449.

Definition.—Sphæroidea with numerous (eight to twelve or more, commonly between twenty and sixty) radial spines on the surface of the spherical shell; living solitary (not associated in colonies).

The family Astrosphærida, the largest and most varied of all Sphæroidea, is distinguished from the other members of this group by the possession of numerous radial spines, which are either regularly or irregularly disposed on the surface of the spherical shell. The extreme variability and richness of form in this family is mainly due to the different size, shape, and disposition of these radial spines.

The simplest Astrosphærida are the Coscinommida, with a single spherical or polyhedral lattice-shell. To this ancestral group all other subfamilies can be opposed as "Astrosphærida composita," since their skeleton is composed of two or more concentric lattice-shells: two in the Haliommida, three in the Actinommida, four in the Cromyommida, five or more in the Caryommida. In these four subfamilies the concentric shells are all simple (not spongy) fenestrated spheres or endospherical polyhedra. In the sixth subfamily, the Spongiommida, the shell is wholly or partially composed of spongy irregular wicker-work, with or without a medullary shell in the centre.

The Number of the Radial Spines in the Astrosphærida is extremely variable, and ranges from eight to forty or more; in many cases more than one hundred. Often each nodal-point of the network develops on the shell surface one spine. Still more frequently the number of the spines is less than that of the nodal-points. In all concentric Astrosphærida, having two or more concentrical shells, we can distinguish "primary spines," as outer prolongations of the inner radial beams connecting the shells, and "secondary spines," developed only on the outer surface of the shell. Naturally the former are of much greater importance than the latter. But we can also often distinguish among the latter larger "main spines" and smaller "by-spines," the latter commonly much more numerous than the former.

The Disposition of the Radial Spines, either regular or irregular, is a subject of great morphological interest, and remains to be exhausted by further observations. The following cases of regular disposition have been observed by me—(A) eight spines, opposite in pairs in four axes corresponding to the four diagonal axes of a cube; (B) nine spines, regularly disposed at equal distances (?) (not opposed in pairs); (C) ten spines, disposed at equal distances (?); (D) twelve spines, regularly disposed, corresponding to the twelve corners of the regular icosahedron; (E) fourteen spines, quite regularly disposed (six corresponding to the three axes of a regular octahedron, eight to the central points of its eight faces); (F) sixteen spines, regularly disposed (?); (G) twenty spines (very common!), either disposed in the same manner (after the law of Johannes Müller) as in the Acantharia (?), or corresponding to the twenty corners of the regular or pentagonal dodecahedron, or disposed in the same manner as in many Larcoidea (Tholonida, &c., to be described afterwards); (H) twenty-four spines, regularly disposed (?); (I) thirty-two spines, quite regularly disposed (twenty corresponding to the twenty corners of the regular dodecahedron, twelve to the central points of its twelve faces); (K) forty spines, nearly regularly (or quite symmetrically?) disposed. If the number of the spines amounts to more than forty, it is as a rule impossible to determine their regular disposition in a satisfactory manner.

Synopsis of the Genera of Astrosphærida.

I. Subfamily Coscinommida. (One single latticed shell.) Spines all simple, not branched and not tubulous. All spines of the same kind, 088. Acanthosphæra.

Larger main spines and smaller by-spines, 089. Heliosphæra.

Spines hollow conical tubes with porous walls, 090. Conosphæra.

Between simple spines the pores prolonged in hollow tubes, 091. Coscinomma.

Spines branched or forked. Spines with lateral branches, 092. Cladococcus.

Spines forked or dichotomous, 093. Elaphococcus.

II. Subfamily Haliommida. (Two concentric latticed shells.) A. Elatommida, one medullary and one cortical shell. All spines equal, simple, 094. Haliomma.

All spines simple, of two different kinds, 095. Heliosoma.

Spines branched, 096. Elatomma.

B. Diplosphærida, both shells cortical. No by-spines, 097. Leptosphæra.

Inner by-spines, 098. Diplosphæra.

Outer by-spines, 099. Drymosphæra.

Outer and inner by-spines, 100. Astrosphæra.

III. Subfamily Actinommida. (Three concentric latticed shells.) Radial spines not branched. All spines equal, 101. Actinomma.

Larger main spines and smaller by-spines, 102. Echinomma.

Radial spines branched or forked, 103. Pityomma.

IV. Subfamily Cromyommida. (Three concentric latticed shells.) Radial spines not branched. All spines equal, 104. Cromyomma.

Larger main spines and smaller by-spines, 105. Cromyechinus.

Radial spines branched or forked, 106. Cromyodrymus.

V. Subfamily Caryommida. (Numerous, five to ten or more, concentric latticed shells.) Two medullary shells and three or more cortical shells (lattice work ordinary), 107. Caryomma.

No medullary shells (lattice work arachnoidal); three-sided prismatic spines, with verticils of three forked branches. (Arachnosphærida.) Triangular meshes, simple bars, without diagonal bars, 108. Arachnopila.

Triangular meshes, simple bars; diagonal bars between the shells, 109. Arachnopegma.

Polygonal meshes, bars branched, 110. Arachnosphæra.

I. Subfamily Coscinommida. (One single latticed shell.)

Spines all simple, not branched and not tubulous.

All spines of the same kind,

88. Acanthosphæra.

Larger main spines and smaller by-spines,

89. Heliosphæra.

Spines hollow conical tubes with porous walls,

90. Conosphæra.

Between simple spines the pores prolonged in hollow tubes,

91. Coscinomma.

Spines branched or forked.

Spines with lateral branches,

92. Cladococcus.

Spines forked or dichotomous,

93. Elaphococcus.

II. Subfamily Haliommida. (Two concentric latticed shells.)

A. Elatommida, one medullary and one cortical shell.

All spines equal, simple,

94. Haliomma.

All spines simple, of two different kinds,

95. Heliosoma.

Spines branched,

96. Elatomma.

B. Diplosphærida, both shells cortical.

No by-spines,

97. Leptosphæra.

Inner by-spines,

98. Diplosphæra.

Outer by-spines,

99. Drymosphæra.

Outer and inner by-spines,

100. Astrosphæra.

III. Subfamily Actinommida. (Three concentric latticed shells.)

Radial spines not branched.

All spines equal,

101. Actinomma.

Larger main spines and smaller by-spines,

102. Echinomma.

Radial spines branched or forked,

103. Pityomma.

IV. Subfamily Cromyommida. (Three concentric latticed shells.)

Radial spines not branched.

All spines equal,

104. Cromyomma.

Larger main spines and smaller by-spines,

105. Cromyechinus.

Radial spines branched or forked,

106. Cromyodrymus.

V. Subfamily Caryommida. (Numerous, five to ten or more, concentric latticed shells.)

Two medullary shells and three or more cortical shells (lattice work ordinary),

107. Caryomma.

No medullary shells (lattice work arachnoidal); three-sided prismatic spines, with verticils of three forked branches. (Arachnosphærida.)

Triangular meshes, simple bars, without diagonal bars,

108. Arachnopila.

Triangular meshes, simple bars; diagonal bars between the shells,

109. Arachnopegma.

Polygonal meshes, bars branched,

110. Arachnosphæra.

VI. Subfamily Spongiommida. (Spherical shell whole or partly spongy, with or without enclosed latticed medullary shells in the centre.) I. Tribe Spongodrymida, without latticed medullary shell. Spongy sphere solid. Spines simple, 111. Spongiomma.

Spines branched, 112. Spongodrymus.

Spongy sphere hollow. Spines simple, 113. Spongechinus.

Spines branched, 114. Spongothammus.

II. Tribe Rhizoplegmida, with one single latticed medullary shell. Medullary shell spherical. Framework arising from the medullary shell, 115. Spongopila.

Framework separate from the medullary shell. No medullary by-spines, 116. Rhizoplegma.

Medullary by-spines, 117. Lychnosphæra.

Medullary shell a simple cube. Framework arising immediately from the medullary shell, 118. Centrocubus.

Framework separate from the medullary shell, 119. Octodendron.

III. Tribe Rhizosphærida, with two concentric latticed medullary shells. Framework arising from the medullary shell, 120. Spongosphæra.

Framework separate from the medullary shell, 121. Rhizosphæra.

VI. Subfamily Spongiommida. (Spherical shell whole or partly spongy, with or without enclosed latticed medullary shells in the centre.)

I. Tribe Spongodrymida, without latticed medullary shell.

Spongy sphere solid.

Spines simple,

111. Spongiomma.

Spines branched,

112. Spongodrymus.

Spongy sphere hollow.

Spines simple,

113. Spongechinus.

Spines branched,

114. Spongothammus.

Medullary shell spherical.

Framework arising from the medullary shell,

115. Spongopila.

II. Tribe Rhizoplegmida, with one single latticed medullary shell.

Framework separate from the medullary shell.

No medullary by-spines,

116. Rhizoplegma.

Medullary by-spines,

117. Lychnosphæra.

Medullary shell a simple cube.

Framework arising immediately from the medullary shell,

118. Centrocubus.

Framework separate from the medullary shell,

119. Octodendron.

III. Tribe Rhizosphærida, with two concentric latticed medullary shells.

Framework arising from the medullary shell,

120. Spongosphæra.

Framework separate from the medullary shell,

121. Rhizosphæra.

Subfamily Coscinommida, Haeckel.

Heliosphærida, Haeckel, 1881, Prodromus, pp. 449, 450.

Definition.—Astrosphærida with one single spherical lattice-shell.

Genus 88. Acanthosphæra,^[122] Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d.

Definition.—Astrosphærida with one simple lattice-sphere, covered with simple radial spines of the same kind.

The genus Acanthosphæra exhibits the most simple form of all Astrosphærida; a simple spherical lattice-shell, the surface of which is covered by radial spines of one and the same kind. The number of the latter is very variable, often twelve to twenty, regularly disposed; in other cases forty to sixty or more; and sometimes at each nodal-point of the network a spine is developed.

Subgenus 1. Rhaphidococcus, Haeckel, 1862, Monogr. d. Radiol., p. 365 (sensu emendato).

Definition.—Pores of the spherical shell regular or subregular, all of nearly equal size and similar form. Radial spines arising from all the nodal-points of the network.

1. Acanthosphæra tenuissima, Haeckel.

Heliosphæra tenuissima, Haeckel, 1862, Monogr. d. Radiol., p. 351, Taf. ix. fig. 2.

Shell extremely thin walled, eight to ten times as broad as one pore. Meshes or pores regular, hexagonal, with thread-like bars; five to seven on the radius. At each nodal-point (between every three meshes) arises a bristle-shaped radial spine, as long as the diameter of one pore.

Dimensions.—Diameter of the shell 0.2 to 0.25, of the meshes or pores 0.025 to 0.03, bars below 0.0001; length of the spines 0.03.

Habitat.—Mediterranean (Messina), North Atlantic (Canary Islands).

2. Acanthosphæra tenuis, n. sp.

Shell very thin walled, about twenty times as broad as one pore. Meshes subregular, hexagonal, with thread-like bars; twelve to fourteen on the radius. At each nodal-point arises a bristle-shaped radial spine, about as long as the radius.

Dimensions.—Diameter of the shell 0.3 to 0.35, pores 0.015 to 0.018, bars below 0.001; length of the spines 0.12 to 0.16.

Habitat.—Central Pacific, Stations 266 to 274, depth 2350 to 2925 fathoms.

3. Acanthosphæra macropora, n. sp.

Shell thin walled, five to six times as broad as one mesh. Pores regular, circular, hexagonally framed, ten to twelve times as broad as the bars. Radial spines bristle-shaped, as long as the diameter of one pore, arising from all the nodal-points.

Dimensions.—Diameter of the shell 0.07 to 0.08, pores 0.012, bars 0.001; length of the spines 0.012.

Habitat.—Central Pacific, Station 271, surface.

4. Acanthosphæra micropora, n. sp.

Shell thick walled, forty to fifty times as broad as one pore. Pores regular, circular, hexagonally framed, half as broad as the bars. Radial spines bristle-shaped, as long as the radius of the shell, arising from all the nodal-points.

Dimensions.—Diameter of the shell 0.22, pores 0.003, bars 0.006; length of the spines 0.1.

Habitat.—South Pacific, Station 288, surface.

5. Acanthosphæra dentata, Haeckel.

Cladococcus dentatus, Haeckel, 1862, Monogr. d. Radiol., p. 367, Taf. xiii. fig. 10.

Shell thin walled, eight to ten times as broad as one pore. Pores regular, circular, hexagonally framed, three times as broad as the bars. Radial spines arising from all the nodal-points of the network, three-sided prismatic, with dentated or serrated edges, longer than the shell diameter.

Dimensions.—Diameter of the shell 0.08, pores 0.01, bars 0.003; length of the spines 0.1, breadth 0.003.

Habitat.—Mediterranean (Messina), surface.

6. Acanthosphæra acufera, Haeckel.

Rhaphidococcus acufer, Haeckel, 1862, Monogr. d. Radiol., p. 366, Taf. xiv. fig. 1.

Cladococcus acufer, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 800.

Shell thin walled, eight to ten times as broad as one mesh. Pores regular, circular, three times as broad as the bars. Radial spines bristle-shaped, arising with thicker conical bases from all the nodal-points, about as long as the diameter of the shell.

Dimensions.—Diameter of the shell 0.08, pores 0.01, bars 0.003; length of the spines 0.08.

Habitat.—Mediterranean (Messina); North Atlantic, Station 354, surface.

7. Acanthosphæra castanea, n. sp. (Pl. 26, fig. 3).

Shell thick walled, thirty times as broad as one mesh. Pores regular, circular, nearly of the same breadth as the bars. Radial spines bristle-shaped, arising with thicker conical bases from all the nodal-points, scarcely half as long as the radius of the shell.

Dimensions.—Diameter of the shell 0.15, pores and bars 0.005; length of the spines 0.03.

Habitat.—North Pacific, Station 244, surface.

8. Acanthosphæra flosculenta, n. sp.

Shell thick walled, thirteen times as broad as one mesh. Pores regular, circular, three times as broad as the bars, with an elegant six-lobed frame (Pl. 28, fig. 1b). In the intervals between the six lobes of each mesh arise six conical radial spines (half as long as the radius), six around each pore. (Differs from the similar Haliomma flosculentum, Pl. 28, fig. 1, in the absence of an enclosed medullary shell and the stronger development of the spines.)

Dimensions.—Diameter of the shell 0.13, pores 0.01, bars 0.003; length of the spines 0.03.

Habitat.—Indian Ocean, Cocos Islands, surface, Rabbe.

Subgenus 2. Rhaphidocapsa, Haeckel.

Definition.—Pores of the spherical shell regular or subregular, all of nearly equal size and similar form. Radial spines scattered at some distance apart, not at all the nodal-points.

9. Acanthosphæra insignis, Haeckel.

Heliosphæra insignis, R. Hertwig, 1879, Organismus der Radiol., p. 40, Taf. v. fig. 7.

Shell thin walled, about ten times as broad as one mesh. Pores regular, hexagonal, ten to twelve times as broad as the bars. Radial spines about one hundred and twenty, arising from certain nodal-points of the network, being as long as the diameter of the sphere, three-sided prismatic, with three thin denticulated edges.

Dimensions.—Diameter of the shell 0.2, pores 0.02, bars 0.002; length of the spines 0.18, breadth 0.003.

Habitat.—Cosmopolitan; Mediterranean (Messina), Atlantic (Stations 325, 347), Indian (Ceylon), Pacific (Stations 270 to 274), surface.

10. Acanthosphæra fortispina, n. sp.

Shell thin walled, about six times as broad as one mesh. Pores subregular, hexagonal, with thread-like bars; three to four on the radius. Radial spines about twenty, three-sided pyramidal, as long as the diameter, and one-third as broad at the base as one pore.

Dimensions.—Diameter of the shell 0.06 to 0.09, pores 0.01 to 0.014, bars below 0.001; length of the spines 0.07 to 0.08, basal breadth 0.03 to 0.04.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

11. Acanthosphæra mucronata, n. sp. (Pl. 26, fig. 7).

Shell thick walled, fifteen times as broad as one pore. Pores regular, circular, hexagonally framed, funnel-shaped, three times as broad as the bars. Radial spines twenty to thirty, dagger-shaped or spindle-shaped, angular, twice as broad in the middle as one pore, about as long as the radius.

Dimensions.—Diameter of the shell 0.11, pores 0.0075, bars 0.0025; length of the spines 0.06, breadth 0.015.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

12. Acanthosphæra clavata, n. sp. (Pl. 26, fig. 8).

Shell thick walled, ten to twelve times as broad as one mesh. Pores subregular, circular, three times as broad as the bars. Radial spines twenty, club-shaped, angular, with prominent edges, twice as broad at the distal end as one pore, about as long as the radius.

Dimensions.—Diameter of the shell 0.11, pores 0.01, bars 0.003; length of the spines 0.06, breadth 0.02.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

13. Acanthosphæra marginata, n. sp.

Shell thick walled, twelve times as broad as one mesh. Pores regular, circular double-edged, four times as broad as the bars. Radial spines conical, fourteen in number, about as long as the radius, and as broad at the base as one mesh. Six spines correspond to the six corners of a regular octahedron, eight to the centre of the eight faces.

Dimensions.—Diameter of the shell 0.1, pores 0.008, bars 0.002; radial spines 0.06, basal breadth 0.01.

Habitat.—Central Pacific, Station 274, surface.

14. Acanthosphæra florida, n. sp.

Shell thick walled, fifteen times as broad as one mesh. Pores regular, circular, hexagonally lobed, separated by prominent funnel-shaped crests of half the breadth. Twenty conical radial spines, half as long as the radius, as broad at the base as one funnel.

Dimensions.—Diameter of the shell 0.15, pores 0.01, bars 0.005; length of the spines 0.04, basal breadth 0.02.

Habitat.—South Atlantic, Station 325, depth 2650 fathoms.

15. Acanthosphæra enneacantha, n. sp.

Shell thin walled, fourteen times as broad as one mesh. Pores regular, circular, twice as broad as the bars. Nine radial spines, regularly disposed, as long as the shell diameter, three-sided prismatic, with pyramidal apex, as broad as one mesh.

Dimensions.—Diameter of the shell 0.14, pores 0.01, bars 0.005; length of the spines 0.15, breadth 0.01.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

16. Acanthosphæra octahedralis, n. sp.

Shell thick walled, octahedral, fourteen times as broad as one mesh. Pores regular, circular, three times as broad as the bars. Fourteen radial spines, regularly disposed, conical, as long as the radius of the shell, twice as broad at the base as one mesh. Six spines correspond to the six corners of a regular octahedron, eight to the central points of its eight faces.

Dimensions.—Diameter of the shell 0.14, pores 0.01, bars 0.003; length of the spines 0.08, basal breadth 0.02.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

17. Acanthosphæra compacta, n. sp.

Shell thick walled, about sixty times as broad as one mesh. Pores regular, circular, twice as broad as the bars. Thirty to forty radial spines, three-sided pyramidal, scarcely half as long as the radius, five to six times as broad at the base as one pore.

Dimensions.—Diameter of the shell 0.24, pores 0.004, bars 0.002; length of the radial spines 0.05, basal breadth 0.02.

Habitat.—Fossil in Barbados.

Subgenus 3. Raphidodrymus, Haeckel.

Definition.—Pores of the spherical shell irregular, of different size or form. Radial spines arising from all the nodal-points of the network.

18. Acanthosphæra capillaris, n. sp.

Shell thin walled, with irregular polygonal meshes, twelve to twenty times as broad as the bars; eight to ten on the radius. Radial spines bristle-shaped, arising from all the nodal-points of the network, about as long as the diameter of the largest meshes.

Dimensions.—Diameter of the shell 0.15 to 0.2, pores 0.012 to 0.02, bars 0.001; length of the spines 0.02.

Habitat.—Central Pacific, Stations 260 to 274, surface.

19. Acanthosphæra arctica, n. sp.

Shell thin walled, with irregular roundish, polygonally framed meshes, three to four times as broad as the bars. Radial spines arising from all the nodal-points of the network, pyramidal at the base; in the distal half bristle-shaped, as long as the radius.

Dimensions.—Diameter of the shell 0.12, pores 0.006 to 0.008, bars 0.002; length of the spines 0.07.

Habitat.—Arctic Ocean, Greenland (in the stomach of Periphylla hyacinthina).

20. Acanthosphæra antarctica, n. sp.

Shell thick walled, with irregular, roundish pores, about as broad as the bars. Radial spines arising from all nodal-points of the network, conical at the base, half as long as the radius.

Dimensions.—Diameter of the shell 0.15, pores and bars 0.005 to 0.008; length of the spines 0.04.

Habitat.—Antarctic Ocean, Station 157, depth 1950 fathoms.

Subgenus 4. Rhaphidosphæra, Haeckel, 1881, Prodromus, p. 450.

Definition.—Pores of the spherical shell irregular, of different size or form. Radial spines scattered at intervals, not at all the nodal-points.

21. Acanthosphæra echinoides, Haeckel.

Cyrtidosphæra echinoides, Haeckel, 1865, Zeitschr. f. wiss. Zool., xv. p. 367, Taf. xxvi. fig. 5.

Shell thin walled, with irregular polygonal or more roundish pores of very different size. Forty to fifty very large meshes, separated by rows of much smaller meshes. Radial spines forty to sixty, half as long as the shell radius, bristle-shaped, with conical bases.

Dimensions.—Diameter of the shell 0.13, larger pores 0.03, smaller 0.003; length of the spines 0.03.

Habitat.—Mediterranean (Nice), surface.

22. Acanthosphæra longispina, n. sp.

Shell thin walled, with irregular polygonal meshes, four to six times as broad as the bars; six to eight on the radius. Thirty to forty radial spines, three-sided prismatic, twice as broad as the bars, twice to three times as long as the diameter of the shell.

Dimensions.—Diameter of the shell 0.12 to 0.15, pores 0.012 to 0.02, bars 0.003; length of the radial spines 0.2 to 0.4, breadth 0.006.