Page:Scientific results HMS Challenger vol 18 part 2.djvu/808

1684 6. Castanella channeri, n. sp.

Pores irregular, roundish, two to four times as broad as the bars. Bristles nearly half as long as the radius. Mouth with seven to nine short conical teeth, shorter than the bristles, but much thicker.

Dimensions.—Diameter of the shell 0.3 to 0.4, of the pores 0.02 to 0.025.

Habitat.—North Atlantic, Stations 352 to 354, surface.

7. Castanella horstoni, n. sp.

Pores irregular, polygonal, three to four times as broad as the bars. Bristles about as long as the radius. Mouth with six stout pyramidal teeth, which are scarcely one-third as long as the radius.

Dimensions.—Diameter of the shell 0.55, of the pores 0.02 to 0.025.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

Definition.—, with simple radial main-spines and a simple smooth mouth.

The genus Castanidium agrees with its ancestral form Castanarium in the simple shape of the smooth and toothless mouth, but differs from it in the possession of long radial main-spines, which are scattered between the constant radial bristles or by-spines of the surface. The shell agrees therefore in its general shape with the Astrosphæride Heliosphæra, as defined above (p. 217, Pl. 26, fig. 9), but differs from it in the possession of the shell-mouth wanting in all.

1. Castanidium willemoesi, n. sp.

Pores regular, circular, hexagonally framed, twice as broad as the bars. Bristles three times as long as the diameter of one pore. Radial main-spines straight, conical, smooth, as long as the radius.

Dimensions.—Diameter of the shell 0.3 to 0.4, of the pores 0.012 to 0.016.

Habitat.—Central Pacific, Station 263 to 274, surface.

2. Castanidium wildi, n. sp.

Pores regular, circular, hexagonally framed, of the same breadth as the bars. Bristles twice as long as one pore. Radial main-spines straight and short, cylindrical, with dimpled surface (as in Pl. 113, fig. 1), as broad as one pore and as long as the diameter of the shell.

Dimensions.—Diameter of the shell 0.66, of the pores 0.045.

Habitat.—South Pacific, Station 297, surface.