Page:Scientific results HMS Challenger vol 18 part 2.djvu/89

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Definition.— with four typical basal feet (two sagittal and two lateral or pectoral feet).

The genus Stephaniscus differs from the preceding Cortiniscus in the production of a fourth (sternal) foot, and therefore exhibits the same relation to it that Stephanium among the Stephanida bears to Cortina. It differs from Stephanium, in the production of a basal ring, with pores or gates between the bases of the basal feet. Two of these feet are sagittal (the posterior caudal and the anterior sternal foot), whilst the other two are lateral or pectoral (right and left). The basal lattice-plate exhibits either two pores ("jugular gates") or four pores (two anterior jugular and two posterior cardinal gates).

1. Stephaniscus tetrapodius, n. sp.

Sagittal ring nearly circular, smooth, with a short conical apical horn. Basal ring square, smooth, with two triangular gates. Four feet simple, equal, conical, divergent, about as long as the diameter of the ring.

Dimensions.—Height of the sagittal ring 0.08, breadth 0.07.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

2. Stephaniscus quadrifurcus, n. sp. (Pl. 92, fig. 14).

Sagittal ring subcircular, thorny with a small thorny apical horn. Basal ring also nearly circular, with two large semicircular gates and a few small thorns. All four feet curved and forked, the fork-branches again ramified, with numerous short curved and pointed branches. The two lateral feet (right and left) are larger and more branched than the two sagittal feet (sternal and caudal foot).

Dimensions.—Height of the sagittal ring 0.12, breadth 0.1.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

3. Stephaniscus quadrigatus, n. sp. (Pl. 92, fig. 15).

Sagittal ring oblique, ovate, with three prominent thorny edges; its dorsal rod nearly straight and vertical, the ventral rod strongly curved; apex with a small curved horn. Basal ring with a few short thorns and four gates of different size; the two anterior (jugular pores) ovate or nearly triangular, two-thirds as broad as the two posterior subcircular or pentagonal (cardinal pores). All