Shell ovate. Pharynx cylindrical, one-fourth as broad as the shell, its inner and outer apertures of equal breadth. The whole surface of the shell, and mainly the outer mouth, is densely covered with thin, curved, siliceous bristles.
Dimensions.—Length of the shell 0.27 to 0.36, breadth 0.2 to 0.3; mouth 0.05 to 0.08.
Habitat.—North Atlantic, Færöe Channel (Gulf Stream), John Murray, depth 600 fathoms.
Genus 697. Pharyngella,[[314]] n. gen.
Definition.—Challengerida with a pharynx, and with one or more teeth on the mouth, but without marginal spines.
The genus Pharyngella differs from the preceding Entocannula, its ancestral form, in the development of one or more teeth on the peristome, and exhibits therefore the same relation to it that Challengeria bears to Lithogromia. Only a few species of this genus have been observed, all in the Atlantic.
1. Pharyngella monoceros, n. sp.
Shell ovate, slightly compressed, with a single large tooth on the dorsal corner of the peristome. The tooth is cylindro-conical, half as long as the shell, straight or slightly curved, and lies in the main axis of the shell. Pharynx cylindrical, straight, half as long as the shell-radius. This species is very similar to Challengeria tritonis (Pl. [99], fig. 5), and to the common cosmopolitan Challengeria naresii, but differs generically from them in the possession of the pharynx.
Dimensions.—Diameter of the shell 0.25 to 0.28; length of the tooth 0.14.
Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.