Page:Scientific results HMS Challenger vol 18 part 2.djvu/700

1576 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.

Dimensions.—Length of the tubes 0.5 to 4.2, breadth 0.003 to 0.02.

Habitat.—North Atlantic, Station 253, Færöe Channel, surface, John Murray.

Definition.— with a veil of tangential needles, and with radial tubes, which bear no lateral branches, but at the distal end a verticil of simple terminal branches.

The genus Aulographis, the richest in the number of species among all Aulacanthida, differs from the preceding Aulacantha, its ancestral form, in the development of simple terminal branches, which form either a fork or a verticil. The branches are either smooth or spiny, but not ramified as in the following genus, Auloceros. Their distal