Page:Scientific results HMS Challenger vol 18 part 2.djvu/345

Rh wings or solid spines arising from the collar stricture, and freely prominent between the horned cephalis and the flat conical thorax.

The genus Eucecryphalus, according to the restricted definition here given, comprises only those Sethopilida in which the three primary cortinar beams are perfectly free divergent collar wings, i.e., free spines arising outside the shell from the collar stricture, between the cephalis and thorax. The type of this genus (which I formerly united with other Sethopilida) remains Eucecryphalus gegenbauri.

Definition.—Peristome or margin of the basal mouth of the thorax smooth, without marginal spines.

1. Eucecryphalus corocalyptra, n. sp.

Shell flatly conical, with slight collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 6. Cephalis subspherical, with an oblique conical horn twice its length. Thorax conical, twice as broad as long, with regular hexagonal meshes and straight lateral outlines. From the collar stricture there arise three slender conical spines, about as long as the thorax, divergent downwards. Similar to Corocalyptra agnesæ (Pl. 59, fig. 3), but without lumbar stricture and abdomen. Peristome or basal margin of the mouth of the thorax smooth, simple.

Dimensions.—Cephalis 0.3 diameter; thorax 0.09 long, 0.18 broad.

Habitat.—Cosmopolitan; Atlantic, Indian, Pacific, surface.

2. Eucecryphalus halicalyptra, n. sp.

Shell flat, campanulate, with distinct collar stricture. Length of the two joints = 1 : 4, breadth = 2 : 10. Cephalis hemispherical, with two divergent conical horns, a major occipital and a minor frontal horn. Thorax with subregular hexagonal meshes and concave-convex lateral outlines, campanulate. From the collar stricture there arise three divergent bristle-shaped spines, nearly horizontal, about half as long as the thorax. Peristome smooth, with a marginal coronal of small square pores.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.08 long, 0.2 broad.

Habitat.—Central Pacific, Stations 266 to 274, surface.

Definition.—Peristome or margin of the basal mouth of the thorax dentate, with a coronal of marginal spines.