Definition.—Semantida 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 Nassellaria, 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, on the outer and upper thorny. Apical horn and the three divergent feet nearly equal, straight, about as long as the sagittal ring, with three thorny edges.
Dimensions.—Height of the sagittal ring 0.1 to 0.12, breadth 0.07 to 0.09.
Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.
2. Cortiniscus dipylaris, n. sp. (Pl. [92], fig. 13).
Sagittal ring nearly semicircular, with prominent distorted edges and six pairs of small roundish papillate tubercles (three pairs on the straight dorsal, three on the curved ventral rod). Apical horn short and stout, with a tuberculate knob. Basal ring smaller than the sagittal ring with two elliptical gates. Three feet short and stout, irregularly branched like a cauliflower, with numerous short papillate tubercles.
Dimensions.—Height of the sagittal ring 0.11, breadth 0.08.
Habitat.—Central Pacific, Station 268, depth 2900 fathoms.