Page:Scientific results HMS Challenger vol 18 part 1.djvu/1009

Rh 4. Porocapsa coronodon, n. sp.

Perspinal holes circular, with ciliated margin, which forms a crown of sixteen to twenty-four thin parallel teeth. Poruli of the shell surrounded by an elevated ring with high crenated margin. Four edges of the spines denticulate.

Dimensions.—Diameter of the shell 0.55; length of the spines 0.15.

Habitat.—Antarctic Ocean, Station 154, surface.

Definition.— with twenty radial spines shorter than the radius of the shell; therefore their distal ends not connected with the twenty perspinal holes, which are prolonged outside into radial tubes (each one in the radial ideal prolongation of one inner spine).

The genus Cannocapsa, exhibits the same peculiar reduction of the radial spines as the foregoing Porocapsa; the spines are also here shorter than the shell-radius and do not therefore reach the perspinal holes of the shell. But whilst these latter are simple in Porocapsa, they are prolonged into radial tubules in Cannocapsa; the outer surface bears therefore twenty such cylindrical tubules, separated by a short distance from the inner enclosed spines, but disposed quite regularly according to the law of Icosacantha.

1. Cannocapsa osculata, n. sp.

Perspinal holes prolonged into short cylindrical tubuli, the length of which about equals their diameter. Both ends of the tubuli with smooth thickened margin. Poruli of the shell simple, without ring and dimple. Four edges of the spines smooth; their length equals about four-fifths of the shell-radius.

Dimensions.—Diameter of the shell 0.24; length of the spines 0.09, of the tubuli 0.01.

Habitat.—North Atlantic, Færöe Channel (Gulf Stream), surface, John Murray.

2. Cannocapsa stethoscopium, n. sp. (Pl. 133, fig. 8).

Perspinal holes prolonged into cylindrical tubuli, half as long as the shell radius. Both ends of the tubuli with smooth thin trumpet-shaped margins. Poruli of the shell simple, without ring and dimple. Four edges of the spines smooth; their length about equals three-fourths of the shell-radius.

Dimensions.—Diameter of the shell 0.2; length of the spines 0.08, of the tubuli 0.05.

Habitat.—South Atlantic (west of Tristan da Cunha), Station 333, surface.

3. Cannocapsa tubulosa, n. sp.

Perspinal holes prolonged into cylindrical tubuli, which are as long as or longer then the shell-radius. Both ends of the tubuli with smooth thickened margin. Poruli of the shell simple,