Page:Scientific results HMS Challenger vol 18 part 2.djvu/573

Rh Dimensions.—Length of the shell (with nine joints) 0.21, breadth 0.08; length of each joint 0.016 to 0.019, of the last joint 0.07.

Habitat.—Western Tropical Pacific, Station 224, depth 1850 fathoms.

Definition.—Shell with three radial combs or longitudinal rows of isolated spines (instead of the three radial ribs).

4. Stichopera pectinata, n. sp. (Pl. 75, fig. 11).

Shell club-shaped, with nine sharp strictures. The nine upper joints increase gradually in length and breadth, and are together three times as long as the inflated, inversely campanulate and rounded last joint. Each joint (excepting the first and the last) bears three thin, bristle-shaped spines, which are directed obliquely upwards. Cephalis subspherical, with a slender, conical horn of twice the length. Pores subregular, in the upper half circular, in the lower hexagonal.

Dimensions.—Length of the shell (with ten joints) 0.22, breadth 0.09; length of the eighth and ninth joints 0.02, of the last joint 0.075.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

5. Stichopera clavata, n. sp.

Shell club-shaped, with eight sharp strictures, very similar in form and structure to that of the preceding species, but differing from it in the club-like form of the inflated last joint, which is nearly half as long as the shell; its lower half is broader than the upper (the reverse being the case in the preceding species). The lateral spines of the three combs are not directed upwards, but downwards. Cephalis with a curved, conical horn of the same length.

Dimensions.—Length of the shell (with nine joints) 0.2, breadth 0.08; length of the eighth joint 0.02, of the last joint 0.09.

Habitat.—South Pacific, Station 298, depth 2225 fathoms.

6. Stichopera verticillata, n. sp.

Shell club-shaped, with ten sharp strictures, similar in form and structure to that of the two preceding species, but differing from them in the ovate form of the slender last joint, which is one-third as long as the whole shell, and five times as long as the preceding joint. The lateral spines of the three combs are directed nearly horizontally, and are much more numerous, each joint (excepting the first and last) bears six to twelve spines (two, three, or four in each radius). They form together about thirty horizontal verticils, each with three spines. Cephalis with a curved, conical horn of three times the length.