Page:Scientific results HMS Challenger vol 18 part 1.djvu/1071

Rh Spines compressed, triangular, gradually tapering towards both ends; outer half a little longer, and much broader than the inner.

Dimensions.—Length of the shell 0.14, breadth 0.12; length of the spines 0.08, basal breadth 0.025.

Habitat.—Central Pacific, Station 274, surface.

Definition.— with forty parmal pores (two on each plate), without dimples and crests, but with numerous by-spines on the surface.

The genus Belonaspis differs from its ancestral genus Thoracaspis only in the possession of numerous superficial by-spines, and bears therefore to it the same relation as Diporaspis does to Dorataspis. The two latter differ from the two former in the spherical form of the central capsule and the enclosing shell, which here becomes ellipsoidal.

1. Belonaspis pandanus, n. sp.

Parmal pores elliptical, three or four times as large as the circular sutural pores. Each plate surrounded by five or six sutural pores (a single one on each side). Spines compressed, triangular; outer part half as long as the inner, and twice as long as the numerous, simple, bristle-shaped by-spines.

Dimensions.—Length of the ellipsoidal shell (or major axis) 0.12, breadth (or minor axis) 0.1; length of the spines 0.03, basal breadth 0.02.

Habitat.—South Pacific, Station 295, surface.

2. Belonaspis furcata, n. sp.

Parmal pores elliptical, twice as broad as the circular sutural pores. Each plate surrounded by five or six sutural pores (a single one on each side). Spines compressed, linear, very thin; outer part longer than the inner. By-spines very numerous, half as long as the radius, furcate, with divergent fork-branches.

Dimensions.—Length of the shell 0.1, breadth 0.08; length of the spines 0.12, breadth 0.003.

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

3. Belonaspis datura, n. sp. (Pl. 139, fig. 9).

Parmal pores elliptical, three or four times as large as the circular sutural pores. Each plate surrounded by ten or twelve sutural pores (two on each side). Spines triangular, two-edged, about