Dimensions.—Length of the tubes 2.0 to 2.5, breadth 0.02 to 0.03; branches 0.08 to 0.12.
Habitat.—South Atlantic, Station 319, depth 2425 fathoms.
8. Auloceros arborescens, n. sp, (Pl. [102], figs. 11, 13).
Radial tubes club-shaped, irregularly curved, thickened towards the distal end. Terminal branches two opposite (rarely three or four), forked near the base, and either dichotomously or more irregularly branched; each tube bears fifteen to thirty, usually twenty to twenty-four, secondary branches, which are irregularly curved, and armed at the distal end with a spathilla of four to eight recurved teeth. The tubes are more richly branched than in the preceding, smaller, closely allied species, and the branches are more flatly expanded.
Dimensions.—Length of the tubes 2.6 to 3.3, breadth 0.03 to 0.04; branches 0.1 to 0.2.
Habitat.—South Pacific, Stations 288 to 295, depth 1500 to 3000 fathoms.
Genus 669. Aulospathis,[[287]] n. gen.
Definition.—Aulacanthida 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.