Page:Scientific results HMS Challenger vol 18 part 2.djvu/513

Rh oblique horn (broken off in the specimen figured). Pores of the thorax polygonal, increasing gradually in size towards the girdle (in three to four circles.) Abdomen nearly horizontally expanded with two rows of pores, the inner with very small and numerous square pores, the outer with twenty to thirty much larger quadrangular pores. Coronal of the peristome with the same number of short, divergent feet, alternating with the larger pores.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.02; breadth, a 0.04, b 0.15, c 0.2.

Habitat.—North Atlantic, Canary Islands (Lanzerote), Station 354, surface.

11. Clathrocyclas jonis, n. sp. (Pl. 59, fig. 9).

Shell campanulate, with two slight strictures. Length of the three joints = 1 : 5 : 2, breadth = 1 : 6 : 8. Cephalis small, hemispherical, with two divergent, conical horns of nearly equal length. Pores of the thorax polygonal, increasing in size towards the girdle; in the upper half filled up by an extremely fine and delicate cobweb-like network. Abdomen with two rows of pores, of the same shape as in the preceding species, also with equal coronal.

Dimensions.—Length of the three joints, a 0.03, b 0.1, c 0.03; breadth, a 0.02, b 0.12, c 0.16.

Habitat.—Central Pacific, Station 274, surface.

12. Clathrocyclas latonæ, n. sp. (Pl. 59, fig. 7).

Shell campanulate, very similar to the preceding species, but flatter and different in the larger cephalis, bearing only a single oblique horn. All the polygonal pores of the thorax are filled out by delicate cobweb-like network. Length of the three joints = 1 : 3 : 1, breadth = 1 : 4 : 6. Abdomen with three circular rows of quadrangular pores; first very small and numerous, second of median size, third very large. Coronal with thirty to forty short triangular feet.

Dimensions.—Length of the three joints, a 0.03, b 0.08, c 0.03; breadth, a 0.03, b 0.12, c 0.18.

Habitat.—Tropical Atlantic, Station 325, surface.

13. Clathrocyclas coscinodiscus, n. sp. (Pl. 58, figs. 3, 4).

Shell flatly campanulate, with two distinct strictures. Length of the three joints = 1 : 5 : 2, breadth = 1 : 8 : 10. Cephalis hemispherical, with two divergent, pyramidal horns of the same length. Thorax with concave outline, with numerous hexagonal pores, gradually increasing in size towards the girdle, except the outermost row (inside the girdle), which is composed of very small, square pores. Abdomen (outside the girdle) with three rows of pores; first with small, second with median, third with large pores. Coronal with eighty to one hundred short, divergent feet.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.03; breadth, a 0.025, b 0.16, c 0.2.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.