Page:Scientific results HMS Challenger vol 18 part 2.djvu/812

1688 confluent. The shell is very similar to the Astrosphæride Cladococcus (compare above p. 223, Pl. 27), but differs from it in the possession of the shell-mouth, absent in all.

1. Castanopsis naresi, n. sp. (Pl. 113, fig. 3).

Pores subregular, circular, about twice as broad as the bars. Bristles twice as long as one pore. Radial main-spines somewhat shorter than the diameter of the shell, straight, cylindrical, in the proximal half simple, in the distal half irregularly branched, each with ten to twelve partly confluent branches.

Dimensions.—Diameter of the shell 0.6 to 0.7, of the pores 0.02 to 0.03.

Habitat.—Tropical Atlantic, Station 347 to 349, surface.

2. Castanopsis macleari, n. sp.

Pores irregular, roundish, two to four times as broad as bars. Bristles half as long as the radius. Radial main-spines about as long as the radius, stout and straight, cylindrical, forked at the distal end, with two or three unequal fork-branches.

Dimensions.—Diameter of the shell 0.42, of the pores 0.015 to 0.03.

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

3. Castanopsis fergusoni, n. sp.

Pores irregular, roundish or polygonal, about as broad as the bars. Bristles three times as long as one pore. Radial main-spines somewhat longer than the diameter of the shell, cylindrical, with irregular and partly confluent lateral branches (similar to Pl. 113, fig. 4a).

Dimensions.—Diameter of the shell 0.55, of the pores 0.012 to 0.016.

Habitat.—North Atlantic, Station 354, surface.

Definition.— with branched radial main-spines and a dentate mouth.

The genus Castanura differs from the preceding Castanopsis in the possession of a corona of teeth surrounding the mouth, similar to that of Castanissa. It differs from the latter in the ramification of the radial main-spines, wherein it agrees with the former. Castanura may therefore be derived either from Castanissa by ramification of the main-spines, or from Castanopsis by development of teeth around the mouth.