with two parallel, triangular pointed teeth, which are obliquely ascending, lamellar, with inflated ovate base, and about as long as the shell-radius.
Dimensions.—Diameter of the shell 0.2 to 0.3, length of the teeth 0.1 to 0.15.
Habitat.—Tropical Atlantic, Stations 347, 348, depth 2250 to 2450 fathoms.
8. Challengeria harstoni, John Murray.
Shell subcircular or somewhat triangular, with convex margins. Peristome with two parallel, slender, lanceolate teeth, which are obliquely ascending, and about half as long as the shell-radius.
Dimensions.—Diameter of the shell 0.15 to 0.18, length of the teeth 0.04 to 0.05.
Habitat.—North Pacific, Station 231, depth 2250 fathoms.
9. Challengeria campbelli, John Murray.
Shell cordate, nearly triangular, compressed, with blunt apex. Peristome in the excavated middle of the broad base, with two short, parallel, triangular teeth. This species is very similar to Porcupinia cordiformis (Pl. 99, fig. 16), but differs from it in the absence of an internal pharynx and of external apical spines.
Dimensions.—Diameter of the shell 0.2 to 0.24; length of the teeth 0.03 to 0.05.
Habitat.—South Atlantic, Stations 332 to 335, depth 1425 to 2200 fathoms.
10. Challengeria thomsoni, John Murray.
Shell ovate, slightly compressed, with rounded apical pole. Peristome semitubular, obliquely ascending, nearly straight, in the lower half an open half-cylinder, in the upper half forked, with two parallel, thin, oblique teeth. Sometimes a third small (dorsal) tooth is developed.
Dimensions.—Length of the shell 0.3 to 0.35, breadth 0.2 to 0.25; length of the peristome 0.08 to 0.12.
Habitat.—South Atlantic, Stations 318 to 330, surface, and in depths from 1900 to 2900 fathoms.
11. Challengeria bidens, n. sp.
Shell ovate, strongly compressed, lenticular. Peristome with two curved, long and thin bristle-shaped teeth, which are obliquely inclined over the mouth, and longer than the radius of the shell.
Dimensions.—Length of the shell 0.12 to 0.18, breadth 0.1 to 0.14; length of the teeth 0.08 to 0.1.
Habitat.—Central Pacific, Stations 271 to 274, depth 2350 to 2750 fathoms.
