4. Aulacantha cannulata, n. sp. (Pl. [105], fig. 16).
Radial tubes cylindrical in the inner proximal half, prismatic in the outer distal half, with from three to six, usually four, prominent, thick, parallel edges, which are dentate towards the thicker distal end; their teeth short, conical, directed outwards, scarcely one-fourth as long as the thickness of the tube. The edges are separated in the distal third by more or less deep furrows, like a channelled column.
Dimensions.—Length of the tubes 1.2 to 2.5, breadth 0.03 to 0.04.
Habitat.—South Pacific, Stations 291 to 293, surface.
5. Aulacantha clavata, n. sp.
Radial tubes more or less irregularly curved, in the inner proximal half slenderly conical, and gradually tapering towards the inflated base, in the outer distal half club-shaped, armed with a few (five to twenty) short conical teeth.
Dimensions.—Length of the tubes 1.0 to 1.2, breadth in the middle pact 0.01, in the distal part 0.04.
Habitat.—South Atlantic, Station 318, depth 2040 fathoms.
6. Aulacantha lævissima, n. sp.
Radial tubes cylindrical, straight, of nearly equal breadth throughout their whole length; the inner proximal end rounded, the outer distal end pointed. Surface of the tubes perfectly smooth, without any teeth. The thickness and length of the simple spicula, as well as the thickness of their wall, are very variable in this species.