Page:Scientific results HMS Challenger vol 18 part 2.djvu/710

1586

Definition.— with a veil of tangential needles, and with radial tubes, which bear two verticils of branches, a distal verticil of terminal branches, and a proximal verticil of lateral branches.

The genus Aulospathis and the following Aulodendron differ from the preceding Aulacanthida in the possession of lateral branches; these are usually similar to the terminal branches, and irregularly scattered along the distal half of the tubes in Aulodendron. In Aulospathis, however, the largest form in the family, each tube bears two whorls or verticils only, a verticil of terminal branches at the distal end, and a verticil of lateral branches beyond the latter, between the middle and distal third of the tube. The number of branches in each verticil is usually from two to four, rarely more; it is, however, very variable, so that the ten species described in the sequel are "Darwinian species," derived either from Aulospathis polymorpha, or from Aulospathis variabilis. Each branch bears at the distal end a spathilla, the teeth of which are very variable in form, number and arrangement.

Definition.—Distal ends of the radial tubes inflated, usually in the form of an ovate or pyriform terminal knob.

1. Aulospathis bifurca, n. sp. (Pl. 104, figs. 1-5).

Radial tubes with an inflated ovate terminal knob at the distal end, which bears two divergent, curved, terminal branches (often a few tubes bear three or four branches instead of the usual two). Proximal whorl usually cruciate, with four irregularly crossed lateral branches (but often with five or six, more rarely with two or three).

Dimensions.—Length of the tubes 0.15 to 25 mm., breadth 0.04 to 0.06; branches 0.1 to 0.15.

Habitat.—South Pacific, Stations 293 to 295, depth 1500 to 2270 fathoms.

2. Aulospathis trifurca, n. sp. (Pl. 104, figs. 6, 7, 7a).

Radial tubes with an inflated ovate terminal knob at the distal end, which bears three divergent, straight, or slightly curved terminal branches (often a few tubes bear two or four branches instead of the usual three). Proximal whorl irregular, usually with six divergent, straight, lateral branches.

Dimensions.—Length of the tubes 2.2 to 3.4, breadth 0.03 to 0.05; branches 0.1 to 0.15.

Habitat.—South Pacific (off Valparaiso), Stations 298 to 300, depth 1375 to 2225 fathoms.