Page:Scientific results HMS Challenger vol 18 part 2.djvu/830

1706

Definition.— with three radial aboral feet, and a variable number of circoral teeth.

The genus Tuscarora comprises seven of the ten observed species of Tuscarorida, all seven agreeing in the possession of three perradial feet, which alternate originally (in four species), with three interradial teeth surrounding the mouth. The latter is armed in two other species with two teeth, and in one species with four teeth (compare above, p. 1704). The three perradial feet have a similar position as in the tripodal, so that they may be distinguished as an odd caudal foot and two paired lateral feet.

Definition.—Shell with three perradial equidistant feet and three interradial equidistant circoral teeth, alternating regularly with the former.

1. Tuscarora bisternaria, John Murray (Pl. 100, figs. 1, 1a).

Tuscarora bisternaria, John Murray, 1879, in litteris, Narr. Chall. Exp., vol. i. p. 226, pl. A, figs. 16, 16a.

Shell subspherical, with three lateral perradial feet in the equatorial zone, and three basal interradial teeth around the mouth, alternating regularly with the former. The three lateral feet arise either in the equator itself or a little above it, and are nearly horizontally expanded, descending a little towards the aboral pole. They are straight, cylindrical, twice to four times as long as the shell, geniculate at the inflated base, and covered with small thorns. A circle of six to eight basal pores in the base of each foot. The narrow mouth is triangular, surrounded by the thorny, inflated, subspherical bases of the three long, cylindrical, diverging, thorny teeth, which ascend obliquely and are longer than the shell; each tooth exhibits in the upper part of the inflated base a corona of eight to ten ovate holes.

Dimensions.—Length of the shell 2.0, breadth 1.5.

Habitat.—Central Pacific, Station 264, depth 3000 fathoms.

2. Tuscarora murrayi, n. sp. (Pl. 100, fig. 2). John Murray, 1876, L. N. 27, pl. 24, fig. 4.

Shell pear-shaped, with three circoral perradial feet in the upper third and three basal interradial teeth around the mouth. The three lateral feet are thin, cylindrical, arcuate, very bristly, arise immediately beyond the narrow tubular peristome, and ascend obliquely nearly to the height of the mouth; then they are curved downwards in a large arc, three to four times as long as