Subfamily 1. Astrocapsida, Haeckel

Definition.—Radial spines connected with the porous shell, as long as or longer than its radius. Therefore the shell pierced by eighty aspinal pores (four around each spine).

Genus 344. Sphærocapsa, Haeckel, 1881, Prodromus, p. 469.

Definition.—Sphærocapsida with twenty radial spines as long as the radius of the shell, without external prolongation; therefore their distal ends inserted in the perspinal holes, each of which is composed of four aspinal pores.

The genus Sphærocapsa is the most common form of the Sphærocapsida, and comprises those species in which the radial spines are as long as the radius of the shell, and therefore are connected with the margin of its aspinal holes, but not prolonged beyond its surface.

1. Sphærocapsa cruciata, n. sp. (Pl. , figs. 6, 7).

Aspinal holes nearly circular, with flat radially striated margin. Four aspinal pores of each hole rounded equilateral triangular. Porules of the shell simple, without ring and dimple. Four edges of the spines smooth.

Dimensions.—Diameter of the shell 0.4 to 0.5, of the central capsule 0.3 to 0.4.

Habitat.—North Atlantic, Færöe Channel (Gulf Stream), 1880, John Murray, surface.

2. Sphærocapsa dentata, n. sp. (Pl. , fig. 9).

Aspinal holes four-lobed, with broad concave margin denticulated on the periphery. Four aspinal pores of each hole pear-shaped, oblong, elevated in the centre. Porules of the shell simple, without ring and dimple. Four edges of the spines denticulate.

Dimensions.—Diameter of the shell 0.3 to 0.4, of the central capsule 0.2 to 0.3.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

3. Sphærocapsa quadrata, n. sp. (Pl. , fig. 8).

Aspinal holes square, with concave umbilicus in the centre, surrounded by a convex denticulated margin. Four aspinal pores of each hole nearly square. Shell-porules with a polygonal elevated smooth ring, in the bottom of a shallow dimple. Four edges of the spines smooth.

Dimensions.—Diameter of the shell 0.22, of the central capsule 0.17.

Habitat.—Indian Ocean, south of Australia, Station 159, surface.

4. Sphærocapsa pavimentata, n. sp. (Pl. , fig. 10).

Aspinal holes four-lobed, with broad concave, irregularly crenated and figured margin. Four aspinal pores of each hole violin-shaped. Porules of the shell surrounded by an irregularly oblong ring with thick elevated, elegantly crenated margin. Four edges of the spines smooth.

Dimensions.—Diameter of the shell 0.36, of the central capsule 0.3.

Habitat.—South-east Pacific (off Valparaiso), Station 298, surface.

Genus 345. Astrocapsa, n. gen.

Definition.—Sphærocapsida with twenty radial spines longer than the radius of the shell, piercing its perspinal holes, with free external prolongation; therefore with four aspinal pores around each spine.

The genus Astrocapsa differs from the preceding Sphærocapsa in the external prolongation of the radial spines piercing the perspinal holes; it assumes therefore the common shape of the Dorataspida more than the other Sphærocapsida do.

1. Astrocapsa tritonis, n. sp.

Aspinal holes circular, with smooth convex margin and four circular aspinal pores. Porules of the shell simple, without ring and dimple. Four edges of the spines smooth, their outer free part about as long as the diameter of the shell.

Dimensions.—Diameter of the shell 0.25; outer length of the spines 0.3.

Habitat.—North Atlantic, Færöe Channel, Gulf Stream (expedition of H.M.S "Triton," August, 1882), John Murray, surface.

2. Astrocapsa stellata, n. sp. (Pl. , fig. 10).

Aspinal holes cruciform, with high crenated margin. Four aspinal pores of each hole egg-shaped. Porules of the shell simple, without ring and dimple. Four edges of the spines denticulate; their outer free part twice to three times as long as the diameter of the shell.

Dimensions.—Diameter of the shell 0.36; outer length of the spines 0.5 to 0.8.

Habitat.—Antarctic Ocean (near Kerguelen), Station 152, surface.

3. Astrocapsa quadrifida, n. sp.

Aspinal holes four-lobed, with four prominent teeth between the four roundish aspinal pores. Porules of the shell surrounded by a high polygonal smooth ring. Four edges of the spines denticulate; their outer free part about as long as the radius of the shell.

Dimensions.—Diameter of the shell 0.28; outer length of the spines 0.15.

Habitat.—North Pacific, Station 241, surface.

4. Astrocapsa coronata, n. sp. (Pl. , fig. 9).

Aspinal holes circular, with a coronet of numerous thin parallel teeth. Porules of the shell in dimples on irregular polygonal small plates, with coronated ring. Four edges of the spines denticulate; their outer free part about twice as long as the diameter of the shell.

Dimensions.—Diameter of the shell 0.4 to 0.5 ; outer length of the spines 1.0 to 1.2.

Habitat.—North Atlantic, Færöe Channel, Gulf Stream (expedition of the "Knight Errant," 1880), John Murray, surface and at depths varying from 10 to 200 fathoms.