Page:Scientific results HMS Challenger vol 18 part 1.djvu/1006

798 1. Sphærocapsa cruciata, n. sp. (Pl. 135, 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. 135, 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. 135, 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. 135, 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.

Definition.— 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.