Page:Scientific results HMS Challenger vol 18 part 1.djvu/1063

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Definition.— with twenty radial spines, each of which is protected by two free external apophyses.

The genus Pantopelta differs from all other Phractopeltida in the development of free protecting apophyses on all twenty radial spines. Only a single specimen of this rare form was seen, and in this all twenty spines exhibited no marked differences in form and size, but were more or less irregularly developed.

1. Pantopelta icosaspis, n. sp. (Pl. 133, fig. 4).

Apophyses of all twenty radial spines with forked anastomosing branches, forming a more or less irregular cup-like fenestrated shield, pierced by a variable number of pores. Distance of the apophyses from the outer shell equal to half its radius. Pores of the outer shell irregular, roundish, four to six times as broad as those of the inner shell. Radial spines compressed, sword-shaped, longer than the radius of the shell.

Dimensions.—Diameter of the outer shell 0.08, of the inner 0.03.

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

Definition.— with twelve simple spines (four equatorial and eight polar), and with eight tropical spines protected by external free apophyses.

The genus Octopelta differs from the other Phractopeltida in the possession of eight shields or pairs of free apophyses outside the outer lattice-shell; the spines bearing these apophyses are the eight tropical spines. The twelve other spines (eight polar and four equatorial) are quite simple, without apophyses.

1. Octopelta cultella, n. sp.

Apophyses of the eight tropical spines simple, compressed, knife-shaped, about as long as their distance from the outer shell. On the base of each spine (in the network of the outer shell) two orthogonal aspinal pores, two to three times as long as the other polygonal pores.

Dimensions.—Diameter of the outer shell 0.08, of the inner 0.03.

Habitat.—Tropical Atlantic, Station 338, surface.