Chapter XI: Literature and History (10)

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 {197}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.

{198}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, {199}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.

{200}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.

{201}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.

{202}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.

{203}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, 4_a_).

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 {204}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 {205}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. {206}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, 1_a_).

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 {207}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.

{208}_Synopsis of the Genera of Astrosphærida._

-------------------------------------------------------------------------
I. Subfamily Coscinommida.
(One single latticed shell.)
-------------------------------------------------------------------------
{ All spines of the same
Spines all simple, not { kind, 88. _Acanthosphæra_.
branched and not {
tubulous. { 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 with lateral
{ branches, 92. _Cladococcus_.
Spines branched or forked.{
{ Spines forked or
{ dichotomous, 93. _Elaphococcus_.
-------------------------------------------------------------------------
II. Subfamily Haliommida.
(Two concentric latticed shells.)
-------------------------------------------------------------------------
{ All spines equal,
{ simple, 94. _Haliomma_.
{
A. Elatommida, one { All spines simple, of
medullary and one cortical{ two different kinds, 95. _Heliosoma_.
shell. {
{ Spines branched, 96. _Elatomma_.

{ No by-spines, 97. _Leptosphæra_.
{
B. Diplosphærida, both { Inner by-spines, 98. _Diplosphæra_.
shells cortical. {
{ Outer by-spines, 99. _Drymosphæra_.
{
{ Outer and inner
{ by-spines, 100. _Astrosphæra_.
-------------------------------------------------------------------------
III. Subfamily Actinommida.
(Three concentric latticed shells.)
-------------------------------------------------------------------------
{ All spines equal, 101. _Actinomma_.
Radial spines not {
branched. { Larger main spines and
{ smaller by-spines, 102. _Echinomma_.

Radial spines branched or forked, 103. _Pityomma_.
-------------------------------------------------------------------------
IV. Subfamily Cromyommida.
(Three concentric latticed shells.)
-------------------------------------------------------------------------
{ All spines equal, 104. _Cromyomma_.
Radial spines not {
branched. { 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_.

{ Triangular meshes,
No medullary shells { simple bars, without
(lattice work { diagonal bars, 108. _Arachnopila_.
arachnoidal); three-sided {
prismatic spines, { Triangular meshes,
with verticils of three { simple bars; diagonal
forked branches. { bars between the 109. _Arachnopegma_.
(Arachnosphærida.) { shells,
{
{ 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 {Spongy {Spines simple, 111. _Spongiomma_.
Spongodrymida, { sphere {
without { solid. {Spines branched, 112. _Spongodrymus_.
latticed {
medullary {Spongy {Spines simple, 113. _Spongechinus_.
shell. { sphere {
{ hollow. {Spines branched, 114. _Spongothammus_.

{Framework arising
{ from the medullary
{ shell, 115. _Spongopila_.
{
{Medullary {Framework {No medullary by-spines,
II. Tribe { shell { separate { 116. _Rhizoplegma_.
Rhizoplegmida, { spherical. { from the {
with { { medullary {Medullary by-spines,
one single { { shell. { 117. _Lychnosphæra_.
latticed {
medullary {Medullary {Framework arising
shell. { shell a { immediately from
{ simple { the medullary
{ cube. { shell, 118. _Centrocubus_.
{ {
{ {Framework separate
{ { from the medullary
{ { shell, 119. _Octodendron_.

{Framework arising
III. Tribe Rhizosphærida, { from the medullary
with two concentric { shell, 120. _Spongosphæra_.
latticed medullary shells. {
{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. Wiss. Berlin, p. 12.

_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.

{210}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.

{211}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. 1_b_). 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.

{212}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 {213}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.

{214}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.

{215}_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.

_Habitat._--North Pacific, Station 253, surface.

23. _Acanthosphæra brevispina_, n. sp.

Shell thick walled, with irregular polygonal meshes, twice to four times as broad as the bars; twelve to sixteen on the radius. Sixty to eighty radial spines, pyramidal, half as long as the radius of the shell, one-fourth as broad at the base.

_Dimensions._--Diameter of the shell 0.2 to 0.22, pores 0.006 to 0.012, bars 0.003; length of the spines 0.05, basal breadth 0.02.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.

24. _Acanthosphæra acanthica_, Haeckel.

_Cenosphæra acanthica_, Stöhr, 1880, Palæontogr., vol. xxvi. p. 86, Taf.
i. fig. 3.

Shell thick walled, with irregular, roundish pores, twice to three times as broad as the bars; seven to nine on the radius. Ten to twenty radial spines pyramidal, shorter than the radius, twice as broad at the base as one mesh.

_Dimensions._--Diameter of the shell 0.12 to 0.16, pores 0.006 to 0.009, bars 0.003; length of the spines 0.04 to 0.06, basal breadth 0.01 to 0.015.

_Habitat._--Fossil in Tertiary rocks of Sicily and Barbados.

25. _Acanthosphæra haliphormis_, Ehrenberg.

_Acanthosphæra haliphormis_, Ehrenberg, 1861, Abhandl. d. k. Akad. d.
Wiss. Berlin, 1872, Taf. ii. fig. 1.

Shell thick walled, with irregular, roundish pores, twice to four times as broad as the bars; four to five on the radius. Twelve to twenty radial spines pyramidal, longer than the radius, scarcely as broad as one mesh at the base.

_Dimensions._--Diameter of the shell 0.11, pores 0.01 to 0.02, bars 0.005; length of the spines 0.06 to 0.08, basal breadth 0.01.

_Habitat._--Arctic Ocean, near Greenland, depth 1000 fathoms.

{216}26. _Acanthosphæra angulata_, n. sp. (Pl. 26, fig. 4).

Shell thin walled; its pores irregular, roundish, with angular, double-edged margin, two to four times as broad as the bars; six to eight on the radius. Twenty to thirty radial spines pyramidal, angular, with prominent edges, shorter than the radius, as broad at the base as one small mesh.

_Dimensions._--Diameter of the shell 0.2, pores 0.02 to 0.04, bars 0.01; length of the spines 0.06, basal breadth 0.02.

_Habitat._--South Atlantic, Station 332, depth 2200 fathoms.

27. _Acanthosphæra conifera_, n. sp.

Shell thick walled, with irregular, roundish pores, twice to five times as broad as the bars; ten to twelve on the radius. Twenty radial spines conical, regularly disposed, half as long as the radius, as broad at the base as one of the largest meshes.

_Dimensions._--Diameter of the shell 0.2, pores 0.008 to 0.02, bars 0.004; length of the spines 0.05, basal breadth 0.02.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.

28. _Acanthosphæra maxima_, n. sp.

Shell thick walled, with irregular, roundish pores, twice to eight times as broad as the bars; twelve to twenty on the radius. Radial spines very numerous (two to three hundred), short, conical, scarcely as long as the diameter of the largest meshes, and one-third as broad.

_Dimensions._--Diameter of the shell 0.3 to 0.4, pores 0.008 to 0.03, bars 0.004; length of the radial spines 0.03, basal breadth 0.01.

_Habitat._--Tropical Atlantic, Station 348, depth 2450 fathoms.

29. _Acanthosphæra simplex_, Haeckel.

_Rhaphidococcus simplex_, Haeckel, Monogr. d. Radiol., 1862, p. 366,
figs. 5, 6.Taf. xiii.

_Cladococcus simplex_, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d.
Wiss. Berlin, p. 800.

Shell thick walled, with irregular, roundish pores, three to six times as broad as the bars; eight to nine on the radius. Forty to sixty radial spines, about as long as the diameter of the shell, three-sided prismatic, not straight, but more or less bent.

_Dimensions._--Diameter of the shell 0.12, pores 0.005 to 0.012, bars 0.0015 to 0.02; length of the spines 0.12, breadth 0.003.

_Habitat._--Mediterranean (Messina), surface, Haeckel.

30. _Acanthosphæra gibbosa_, n. sp.

Shell thin walled, rugged or tuberculate, covered by about twenty hill-shaped tubercles or protuberances with flat valleys between them. Network very delicate, with thread-like bars and {217}irregular, polygonal pores; twenty to thirty on the radius. Radial spines very numerous, bristle-shaped, twice to three times as long as the diameter of the pores.

_Dimensions._--Diameter of the shell 0.3, pores 0.01 to 0.02; length of the spines 0.02 to 0.05.

_Habitat._--Central Pacific, Station 274, surface.

31. _Acanthosphæra reticulata_, n. sp. (Pl. 26, fig. 5).

_Rhaphidosphæra reticulata_, Haeckel, 1881, Prodromus.

Shell thick walled, with irregular, roundish pores, twice to four times as broad as the bars; six to eight on the radius. Surface of the bars covered with a peculiar delicate network of very fine crests. Twenty to forty radial spines, angular, pyramidal, scarcely one-third as long as the radius of the shell, as broad at the base as the bars.

_Dimensions._--Diameter of the shell 0.22, pores 0.02 to 0.04, bars 0.01; length of the spines 0.04, basal breadth 0.01.

_Habitat._--Central Pacific, Station 271, depth 2425 fathoms.

Genus 89. _Heliosphæra_,[123] Haeckel, 1862, Monogr. d. Radiol., p. 350 (_sensu emendato_).

_Definition._--#Astrosphærida# with one simple lattice-sphere, covered with simple radial spines of two different kinds: larger main spines and smaller by-spines.

The genus _Heliosphæra_ (in the mended definition here employed) differs from the foregoing _Acanthosphæra_ in the possession of two different kinds of radial spines: larger main spines scattered on the surface or disposed regularly in limited numbers (twelve to twenty, sometimes forty to fifty or more), and smaller by-spines in much larger numbers, arising from all the nodal-points of the network (or sometimes also from its bars).

Subgenus 1. _Heliosphærella_, Haeckel.

_Definition._--Pores of the shell regular or subregular, all of nearly equal size and similar form.

1. _Heliosphæra hexagonaria_, n. sp. (Pl. 26, fig. 2).

Shell very thin walled, about twenty times as broad as one pore. Meshes or pores subregular, hexagonal, with thread-like bars; fifteen to seventeen on the radius. Radial spines at the nodal-points of the network; about forty main spines three-sided pyramidal, half as broad at the base as one pore, and twice as long as the bristle-shaped by-spines, which are very numerous, and as long as the diameter of one pore.

{218}_Dimensions._--Diameter of the shell 0.25 to 0.3, of the meshes or pores 0.012 to 0.015, bars below 0.001; length of the main spines 0.03, basal breadth 0.007.

_Habitat._--Central Pacific, Stations 272 to 274, depth 2350 to 2750 fathoms.

2. _Heliosphæra actinota_, Haeckel.

_Heliosphæra actinota_, Haeckel, 1862, Monogr. d. Radiol., p. 352, Taf.
ix. fig. 3.

Shell very thin walled, about ten times as broad as one mesh. Pores regular, hexagonal, with thread-like bars; six to eight on the radius. Radial spines at the nodal-points of the network, bristle-shaped, scarcely broader than the bars; about twenty main spines as long as the diameter of the shell, and numerous by-spines, only one-third to one-half as long as the former.

_Dimensions._--Diameter of the shell 0.2 to 0.25, of the meshes 0.02 to 0.03, bars below 0.001; length of the main spines 0.2 to 0.3.

_Habitat._--Mediterranean (Messina), Atlantic (Canaries, Azores), surface.

3. _Heliosphæra echinoides_, Haeckel.

_Heliosphæra echinoides_, Haeckel, 1862, Monogr. d. Radiol., p. 352, Taf.
ix. fig. 4.

Shell thin walled, about six times as broad as one mesh. Pores regular, hexagonal, eight times as broad as the bars. Radial spines arising, not from the nodal-points of the network, but from the midst of the bars (very rare disposition!); twenty main spines regularly disposed, as long as the radius, four times as long as the numerous by-spines; all spines bristle-shaped, of the same breadth as the bars.

_Dimensions._--Diameter of the shell 0.09, pores 0.015, bars 0.002; length of the main spines 0.04.

_Habitat._--Mediterranean (Messina), surface, Haeckel.

4. _Heliosphæra elegans_, Haeckel.

_Heliosphæra elegans_, Haeckel, 1862, Monogr. d. Radiol., p. 353, Taf.
ix. fig. 5.

Shell very thin walled, about ten times as broad as one mesh. Pores regular, hexagonal, with thread-like bars, which are crossed by tangential bars, so that each side of a hexagon exhibits a regular rectangular cross (exactly the same as in Pl. 19, fig. 5). All radial spines bristle-shaped, as thin as the bars, and arising from the nodal-points; twenty main spines as long as the radius, numerous by-spines scarcely one-sixth as long.

_Dimensions._--Diameter of the shell 0.26, pores 0.026, bars below 0.001; length of the main spines 0.13.

_Habitat._--Mediterranean (Messina), surface, Haeckel.

5. _Heliosphæra pectinata_, n. sp. (Pl. 26, fig. 9).

_Acanthosphæra pectinata_, Haeckel, 1881, Atlas.

Shell thick walled, combed, about fourteen times as broad as one mesh. Pores subregular, circular, with elevated hexagonal frames, three times as broad as the bars. Radial spines very {219}numerous and stout; thirty to forty main spines, three-sided pyramidal, nearly as long as the radius, as broad as one mesh; by-spines small, conical, everywhere scattered at the nodal-points of the network and on the high combs of the bars.

_Dimensions._--Diameter of the shell 0.16, pores 0.012, bars 0.004; length of the main spines 0.07, basal breadth 0.016.

_Habitat._--West Tropical Pacific, Station 225, depth 4475 fathoms.

6. _Heliosphæra coronata_, n. sp. (Pl. 26, figs. 6, 6_a_).

_Acanthosphæra coronata_, Haeckel, 1881, Atlas.

Shell thick walled, about ten times as broad as one mesh. Pores regular, circular, five times as broad as the bars; each pore surrounded by a regular coronal of six short, conical by-spines (fig. 6_a_); twenty to thirty main spines, also conical, half as long as the radius, as broad as one pore.

_Dimensions._--Diameter of the shell 0.15, pores 0.015, bars 0.003; length of the main spines 0.04, basal breadth 0.015.

_Habitat._--Central Pacific, Station 272, depth 2600 fathoms.

7. _Heliosphæra floribunda_, n. sp.

Shell thick walled about ten times as broad as one mesh. Pores regular, six-lobed, twice as broad as the bars; each pore surrounded by six small conical by-spines (as in Pl. 28, figs. 1, 1_b_); twenty main spines regularly disposed cylindro-conical, as long as the diameter of the shell or longer.

_Dimensions._--Diameter of the shell 0.15, pores 0.015, bars 0.008; length of the main spines 0.16, breadth 0.008.

_Habitat._--Central Pacific, Station 268, depth 2900 fathoms.

8. _Heliosphæra cristata_, n. sp.

Shell thick walled, about twelve times as broad as one mesh. Pores subregular, circular, twice as broad as the bars; each pore surrounded by an elegant coronal of ten to twenty small, conical by-spines; twenty main spines regularly disposed, conical, only one-third as long as the radius, as broad at the base as one mesh.

_Dimensions._--Diameter of the shell 0.25, pores 0.02, bars 0.01; length of the main spines 0.04, basal breadth 0.02.

_Habitat._--South Pacific, Station 285, depth 2375 fathoms.

9. _Heliosphæra castanella_, n. sp.

Shell thick walled, about twenty times as broad as one mesh. Pores regular, circular, of the same breadth as the bars. Whole surface densely covered with innumerable bristle-shaped by-spines, half as long as the radius; fifty to eighty main spines, conical, nearly as long as the diameter, {220}twice as broad at the base as one pore. (Very similar to some species of Castanella, Pl. 113, but without the osculum characteristic of this Phæodarian; may be easily confounded with it.)

_Dimensions._--Diameter of the shell 0.3, pores 0.015, bars 0.015; length of the main spines 0.25, basal breadth 0.03.

_Habitat._--North Pacific (Japan), Station 234, surface.

Subgenus 2. _Heliosphæromma_, Haeckel.

_Definition._--Pores of the shell irregular, of different size or form.

10. _Heliosphæra polygonaria_, n. sp.

Shell very thin walled, with thread-like bars and irregular, polygonal pores (having four to eight angles, commonly five to seven); eight to ten on the radius. Radial spines at all the nodal-points of the network, bristle-shaped; forty to sixty main spines, as long as the radius, twice as thick as the numerous by-spines, which are not larger than one mesh.

_Dimensions._--Diameter of the shell 0.15 to 0.2, pores 0.012 to 0.02, bars 0.001; length of the main spines 0.08 to 0.1.

_Habitat._--Central Pacific, Stations 266 to 272, surface.

11. _Heliosphæra heteracantha_, n. sp.