Definition.—Challengerida with a pharynx, or an internal prominent mouth tube.
Genus 696. Entocannula,[[313]] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.
Definition.—Challengerida with a pharynx, without teeth on the mouth, and without marginal spines.
The genus Entocannula and the two following genera represent together the subfamily Pharyngellida, differing from the preceding Lithogromida in the development of a peculiar pharynx, an internal, cylindrical, or funnel-shaped tube, which is conspicuous, leads from the mouth into the shell-cavity, and is provided with an inner and an outer opening. The Pharyngellida are much rarer than the Lithogromida; only ten species have been observed of the former, fifty of the latter. Entocannula is the simplest form of the Pharyngellida, having a smooth shell, without aboral teeth and marginal spines; it differs from Lithogromia only in the possession of the pharynx. One remarkable species is covered entirely with extremely thin, flinty hairs, and may represent therefore a peculiar genus, Trichogromia.
1. Entocannula circularis, n. sp.
Shell circular or nearly circular, lenticular, strongly compressed. Pharynx cylindrical, one-third or one-fourth as broad as the shell, twice as broad as long, its outer and inner apertures of equal breadth. Surface smooth.
Dimensions.—Diameter of the shell 0.20 to 0.32, of the pharynx 0.07 to 0.09.
Habitat.—North Pacific, Station 250, depth 3050 fathoms.
2. Entocannula subglobosa, n. sp.
Challengeria bromleyi, (partim), John Murray, 1879, in schedulis Chall. Coll.