Page:Scientific results HMS Challenger vol 18 part 2.djvu/498

1374 10. Alacorys octacantha, n. sp.

Shell spiny, with deep collar stricture. Length of the three joints = 2 : 8 : 6, breadth = 3 : 7 : 7. Cephalis ovate, with a short, conical horn. Thorax pear-shaped, spiny, with regular, circular pores, similar to Cycladophora erinaceus, Ehrenberg (1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xviii. fig. 2). Abdomen truncate, conical, with irregular, roundish pores, and eight stout, straight, thorny, divergent ribs of equal size, which are prolonged into eight free, conical, spiny feet of the same length.

Dimensions.—Length of the three joints, a 0.04, b 0.16. c 0.12; breadth, a 0.06, b 0.14, c 0.14.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Definition.—Peristome armed with nine feet, three of which are primary or perradial, the other six secondary or interradial.

11. Alacorys enneacantha, n. sp.

Shell papillate, with slight collar stricture. Length of the three joints = 2 : 4 : 8, breadth = 3 : 6 : 9. Cephalis hemispherical, with a stout, conical horn of twice the length. Thorax campanulate, with subregular, circular pores, and small, conical papillæ. Thorax wider, campanulate, with circular pores, and conical papillæ of three times the size. Peristome with nine widely divergent, little curved, conical feet, about as long as the shell. Similar to Podocyrtis ventricosa, Ehrenberg (1875, loc. cit., Taf. xvi. fig. 3), different mainly in the feet.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.03, b 0.06, c 0.09.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

12. Alacorys gigas, n. sp.

Shell thorny, with distinct collar stricture. Length of the three joints = 1 : 4 : 2, breadth = 1 : 5 : 4. Cephalis ovate, with a short, conical horn of about half the length. Thorax campanulate, thorny, with small, regular, circular pores, very similar to Cycladophora gigas, Ehrenberg (loc. cit., 1875, p. 68, Taf. xviii. fig. 1). Abdomen truncate, conical, smooth, with irregular, roundish pores, and nine stout and straight, little divergent ribs, which are prolonged into nine cylindrical, pointed feet of the same length.

Dimensions.—Length of the three joints, a 0.05, b 0.2, c 0.1; breadth, a 0.05, b 0.25, c 0.2.

Habitat.—Fossil in Barbados.

Definition.—Peristome with numerous (ten to twenty or more) prominent feet, three or four of which are primary and perradial, the others secondary and interradial.