Page:Scientific results HMS Challenger vol 18 part 2.djvu/176

1052 and sternal) larger, about half as long as the shell (shortened in the figure). The two sternal feet larger than the two small or rudimentary tergal feet.

Dimensions.—Shell 0.15 long, 0.13 broad; feet 0.02 to 0.06 long.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Definition.— pentapoda, with five descending basal feet, one odd caudal foot, and two pairs of lateral feet (two anterior or pectoral, and two posterior or tergal feet).

Definition.— with five basal feet and one apical horn.

The genus Clathrospyris and the two following closely allied genera represent together the small subfamily of Pentaspyrida, differing from the other Zygospyrida in the possession of five descending feet on the basal face. Three of these are the primary cortinar feet (of Cortiniscus, Plagoniscus, Tripospyris, &c.), whilst the two others are secondary tergal feet. The Pentaspyrida may therefore be probably derived from the Hexaspyrida by loss of the odd anterior or sternal foot.

1. Clathrospyris camelopardalis, n. sp.

Shell nut-shaped, tuberculate, with deep sagittal stricture. Pores irregular roundish. Basal plate with six pores (?). Two pectoral feet very large, twice as long as the shell, cylindrical, curved. Two tergal feet half as long and thick as the pectoral. Caudal foot and apical horn straight, conical, half as long as the shell.

Dimensions.—Shell 0.07 long, 0.09 broad; horn and odd caudal foot 0.04 long; pectoral feet 0.16, tergal 0.08 long.

Habitat.—South Pacific, Station 297, depth 1775 fathoms.

2. Clathrospyris pyramidalis, n. sp. (Pl. 95, fig. 9).

Shell four-sided pyramidal, truncate, thorny, with a slight sagittal stricture. Pores very large, polygonal roundish. Two pairs of large pores on each side of the ring (at the frontal and the occipital plate). Lateral pores more numerous. Basal plate with four large pores. The four edges of the pyramid are prolonged into four short pyramidal divergent lateral feet (one-third as