Page:Scientific results HMS Challenger vol 18 part 2.djvu/87

Rh 5. Clathrocircus dictyospyris, n. sp. (Pl. 92, fig. 9).

Sagittal ring ovate, thorny, with eight pairs of pores. The four apical and the four basal pores are elliptical and far larger than the four dorsal and the four ventral pores. Resembles a Dictyospyris with open lateral gates.

Dimensions.—Height of the sagittal ring 0.08, breadth 0.06.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

6. Clathrocircus multiforis, n. sp. (Pl. 92, fig. 10).

Sagittal ring circular, smooth, with ten to twelve pairs of roundish pores, forming together a complete lattice-girdle with two parallel circular rows of pores. Four larger of these are the four gates of the basal ring (two jugular and two cardinal pores).

Dimensions.—Diameter of the ring 0.1 to 0.15, breadth 0.03 to 0.05.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.

Definition.— with large, typical, regularly disposed basal feet (originally three cortinar feet, one odd caudal and two paired pectoral).

Definition.— with three typical basal feet (an odd caudal foot and two paired lateral or pectoral feet).

The genus Cortiniscus is of peculiar importance, as the common ancestral form of the Cortiniscida, or those Semantida in which the basal ring is provided with typical, regularly disposed basal feet—three, four, or six. Since these typical basal feet (or "cortinar feet") are preserved in the greater number of all, determining their triradial structure, they possess a great morphological value. Cortiniscus exhibits the same three primary feet as Cortina, from which it differs in the production of two or more basal pores (between the odd caudal and the paired lateral feet).

1. Cortiniscus tripodiscus, n. sp. (Pl. 92, fig. 11).

Sagittal ring ovate, thorny, with three prominent, distorted edges; its dorsal rod nearly straight and vertical, with one or two pairs of short thorns; its ventral rod strongly curved, with three or four pairs of divergent thorns. Basal ring larger than the sagittal ring, with two semicircular gates and obliquely ascending halves, which on the inner and lower edge are smooth,