Page:Scientific results HMS Challenger vol 18 part 2.djvu/447

Rh latter, three free, radial spines, or simple wings, corresponding to the three basal feet of Cortina, arise from the collar stricture between the small hemispherical cephalis and the large, flatly conical thorax. Corocalyptra differs from Eucecryphalus, its ancestral form, in the development of a flat and broad abdomen, which is a prolongation of the thorax, and may be compared to the brim of a hat.

1. Corocalyptra agnesæ, n. sp. (Pl. 59, fig. 3).

Shell flatly conical or hat-shaped. Length of the three joints = 1 : 4 : 2, breadth = 2 : 8 : 12. Cephalis hemispherical, with an oblique, small, conical horn of the same length. From the slight collar stricture arise three slender, conical feet of equal length, twice as long as the apical horn, nearly horizontally divergent. Lateral outline of the conical thorax straight, of the flatter abdomen convex; the smooth margin of the abdomen turned inwards. Network delicate, with subregular, hexagonal pores.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.04; breadth, a 0.03, b 0.15, c 0.24.

Habitat.—Central Pacific, Station 270, surface.

2. Corocalyptra elisabethæ, n. sp. (Pl. 59, fig. 10).

Shell flatly conical, hat-shaped, very similar to the preceding species, but with different proportions. Length of the three joints = 1 : 4 : 2; breadth = 1 : 7 : 10. Cephalis very small, with an oblique horn of the same length. The three feet are of different sizes, the caudal odd foot being twice as long as the two lateral, which are equal to the horn. Lateral outline of the campanulate thorax convex, of the flatter abdomen less convex. Margin of the mouth flat.

Dimensions.—Length of the three joints, a 0.015, b 0.06, c 0.03; breadth a 0.02, b 0.14, c 0.2.

Habitat.—Tropical Atlantic, Station 347, surface.

3. Corocalyptra emmæ, n. sp. (Pl. 59, fig. 4).

Shell nearly conical, hat-shaped. Length of the three joints = 1 : 3 : 1, breadth = 1 : 5 : 7. Cephalis hemispherical, with a straight horn of the same length. Feet of the collar larger than in the preceding species, the two lateral smaller being directed upwards, the larger odd caudal downwards. Thorax slightly campanulate; its hexagonal meshes two to four times as large as those of the short, convex abdomen, which is turned inwards.

Dimensions.—Length of the three joints, a 0.02, b 0.09, c 0.03; breadth, a 0.025, b 0.13, c 0.17.

Habitat.—Central Pacific, Station 273, surface.

4. Corocalyptra margarethæ, n. sp.

Shell nearly conical, hat-shaped, very similar to the preceding species, but with much more delicate hexagonal network, with thread-like bars. Length of the three joints = 1 : 7 : 2, breadth =