Page:Scientific results HMS Challenger vol 18 part 2.djvu/183

Rh 2. Therospyris felis, n. sp. (Pl. 89, fig. 6).

Shell nut-shaped, mammillate, with sharp sagittal stricture. Pores large, irregularly roundish or polygonal, of somewhat different size. Basal plate with four large pores. Surface covered with hemispherical pointed mammillæ. Four feet equal, divergent, half as long as the shell, at the distal end forked, with few small branches.

Dimensions.—Shell 0.1 long, 0.15 broad; feet 0.05 long.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

3. Therospyris leo, n. sp. (Pl. 89, fig. 5).

Shell nearly cubical, papillate, with slight sagittal stricture. Pores irregular, roundish; on each side of the ring three pairs of larger pores (the undermost the largest). Basal plate with two large pores. Surface covered with conical papillæ. Four feet equal, divergent, about as long as the shell, with an external spur in the middle, and irregularly branched spines at the distal end.

Dimensions.—Shell 0.08 long, 0.12 broad; feet 0.09 long.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Definition.— polypoda, with numerous descending basal feet (at least seven to nine, usually twelve to sixteen or more).

Definition.— with numerous (seven to twelve or more) basal feet and one apical horn.

The genus Petalospyris and the following three genera form together the peculiar subfamily of Polyspyrida, differing from the other Zygospyrida in the multiplication of the radial feet, which descend from the basal face of the shell; they may therefore be also called "Zygospyrida multiradiata," and bear the closest relationship to the Archiphænida (or the "Monocyrtida multiradiata"). They differ, however, from the latter in the presence of the distinct sagittal stricture, characteristic of all. The number of the basal feet, which form a coronet around the margin of the basal plate, is commonly between twelve and sixteen, but often more. Their form is usually flat, lamellar, but often also more or less cylindrical or conical.