1. Tuscarusa medusa, n. sp. (Pl. [100], figs. 7, 7a).
Shell ovate, with four crossed lateral feet in the upper third, and with two opposite teeth around the mouth. The four feet are opposite in pairs in two diameters of the shell, perpendicular one to another, and arise between the upper and middle third of the shell; they are thin, cylindrical, spinulate, arcuate, and ascend to the height of the mouth diverging upwards; then they are curved downwards in a large arc. They lie in the diagonals of the square, which is halved by the narrow and long fissure of the mouth. This lies in the original sagittal plane, and from its two corners arise the two opposite teeth (a dorsal and a ventral), diverging upwards, cylindrical and slightly curved. The base of each foot is pierced by four pedal pores, of each tooth by two dental pores.
Dimensions.—Length of the shell 1.2, breadth 1.0.
Habitat.—North Pacific, Station 253, depth 3125 fathoms.
Genus 719. Tuscaridium,[[335]] n. gen.
Definition.—Tuscarorida without radial aboral feet, but with a terminal axial caudal foot, and a variable number of circoral teeth.
The genus Tuscaridium, comprising two closely allied species, differs from the two preceding genera of Tuscarorida in the absence of lateral radial feet, which are represented by a single large caudal spine placed in the main axis of the shell, at its aboral pole. The shell is therefore spindle-shaped, and not ovate or subspherical, as in the two other genera. It reaches in the two observed species a length of more than 3 mm.
1. Tuscaridium cygneum, Haeckel.
Tuscarora cygnea, John Murray, 1879, in litteris, Narr. Chall. Exp., vol. i. p. 226, pl. A, fig. 20.
Shell spindle-shaped, twice as long as broad (in the transverse section circular), equally tapering towards both poles of the main axis. The aboral pole bears a thin, cylindrical, straight, caudal spine, placed in the prolongation of the main axis, and about half as long as the shell. Its base is pierced by two large opposite pedal pores. The anterior or oral pole bears a cylindrical peristome, similar to a bird's head, and curved towards the ventral face; on both sides of its neck (at right and left) a series of three or four irregular, ovate, buccal holes. The neck bears four cylindrical, spinulate, radial tubes (two on each side), crossed nearly horizontally, and placed in two diagonal planes perpendicular one to another; these planes correspond to those in which the four feet of Tuscarusa medusa lie. The base of each tube is pierced by four dental pores.