Page:Scientific results HMS Challenger vol 18 part 2.djvu/211

Rh 1. Phormospyris tricostata, n. sp. (Pl. 83, fig. 15).

Cephalis nut-shaped, thorny, with deep sagittal and collar strictures, half as large as the pyramidal thorax. Mouth of the latter dilated and ciliated, twice as broad as the cephalis. Pores irregular, polygonal, with thin bars. Three cylindrical, straight, divergent ribs descend in the wall of the thorax, and are prolonged over the mouth into three short conical teeth.

Dimensions.—Cephalis 0.06 long, 0.09 broad; thorns 0.08 long, 0.16 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Phormospyris tridentata, n. sp. (Pl. 95, fig. 18).

Cephalis nut-shaped, with deep sagittal and collar strictures, about twice as large as the thorax. Mouth of the latter half as broad as the cephalis. Pores very small and numerous, subregular, circular. Collar plate with four large triangular pores. In the wall of the thorax three vertical prismatic ribs descend, which are prolonged over the mouth into three parallel feet of the same length.

Dimensions.—Cephalis 0.06 long, 0.08 broad; thorns 0.04 long, 0.06 broad.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

3. Phormospyris trifoliata, n. sp.

Cephalis nut-shaped, with deep sagittal and collar strictures, smaller than the thorax. Mouth of the latter nearly as broad as the cephalis. Pores circular, double-contoured, larger in the thorax than in the cephalis. The thorax has no lateral ribs, but bears around the mouth three large triangular lamellar terminal feet.

Dimensions.—Cephalis 0.04 long, 0.05 broad; thorax 0.06 long, 0.05 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Definition.— with a corona of numerous (nine to twelve or more) basal feet.

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

The genus Patagospyris and the two following closely allied genera differ from the two preceding tripodal genera in the multiplication of the basal feet, and therefore have to the latter the same relation that the Polyspyrida (Petalospyris) bear to the Tripospyrida (Tripospyris). When the numerous basal feet of Petalospyris become connected by lattice-work, Patagospyris arises.