Page:Scientific results HMS Challenger vol 18 part 2.djvu/499

Rh 13. Alacorys dodecantha, n. sp.

? Podocyrtis schomburgkii, var., Bury, 1862, Polycystins of Barbados, Taf. xii. fig. 3.

Shell smooth, with slight collar stricture. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 7. Cephalis ovate, with a conical horn of the same length. Thorax campanulate, with regular, circular pores. From its margin arise twelve stout, little curved, radial beams, which are widely divergent, and connected in the middle part by a transverse circular ring, so that the abdomen exhibits twelve large triangular holes, and at the peristome, alternating with these, twelve free conical feet of the same length.

Dimensions.—Length of the three joints, a 0.04, b 0.09, c 0.11; breadth, a 0.03, b 0.12, c 0.22.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms; also fossil in Barbados.

14. Alacorys carcinus, n. sp. (Pl. 74, fig. 9).

Calocyclas carcinus, Haeckel, 1879, Atlas, ''loc. cit.''

Podocyrtis schomburgkii, var., Bury, 1862, Polycystins of Barbados, pl. i. fig. 2; pl. xii. fig. 4.

Shell rough, with distinct collar stricture. Length of the three joints = 1 : 4 : 4, breadth = 2 : 6 : 6. Cephalis hemispherical, with a large, cylindrical, bent spine of three times the length. Thorax inflated, campanulate, with large, regular, circular pores. Abdomen truncate, conical, with three to four transverse rows of regular, square pores, produced by eighteen divergent, straight ribs, which are connected by three to four horizontal rings. Distal end of the ribs prolonged into eighteen slender, conical feet, which are about as long as the thorax and slightly curved inwards.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.08; breadth, a 0.05, b 0.12, c 0.12.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms; also fossil in Barbados.

15. Alacorys polyacantha, n. sp.

Shell spiny, with deep collar stricture. Length of the three joints = 3 : 9 : 10, breadth = 4 : 12 : 16. Cephalis hemispherical, with a stout conical horn of the same length. Thorax campanulate, with regular, circular pores and conical spines, increasing in size towards the deep lumbar stricture. Abdomen truncate, conical, with twenty to thirty divergent, straight ribs, which are connected by four to six transverse rings, and prolonged into free conical feet of half the length. Therefore four to six transverse rings of regular, square pores occur.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.1; breadth, a 0.04, b 0.12, c 0.16.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

16. Alacorys ornata, Haeckel.

Cryptoprora ornata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. v. fig. 8.

Shell ovate, smooth, without external strictures, but with two internal annular septa. Length of the three joints = 3 : 5 : 4, breadth = 3 : 6 : 5. Cephalis subspherical, partly enclosed by the uppermost part of the thorax, without horn, or with a small rudimentary horn. Pores subregular,