Habitat.—Antarctic Sea, Station 157, depth 1950 fathoms.
Subfamily 2. Aulographida, Haeckel.
Definition.—Aulacanthida with an external veil of interwoven, very numerous and thin, hollow, tangential needles, entirely covering the surface of the calymma.
Genus 666. Aulacantha,[[284]] Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 799.
Definition.—Aulacanthida with a veil of tangential needles, and with simple radial tubes, which bear neither lateral nor terminal branches.
The genus Aulacantha, hitherto the only representative of this family, was founded by me in 1860 for the cosmopolitan Aulacantha scolymantha, the most common and most widely distributed of all the members of the family. It is the simplest form of the Aulographida, or of those Aulacanthida in which the spherical surface of the calymma is densely covered with interwoven tangential needles. The large radial tubes of Aulacantha possess a very simple shape, as in the preceding Aulactinium, and have neither lateral nor terminal branches.
1. Aulacantha scolymantha, Haeckel.
Aulacantha scolymantha, Haeckel, 1862, Monogr. d. Radiol., p. 263, Taf. ii. figs. 1, 2, Taf. iv. figs. 1-5.
Aulacantha scolymantha, R. Hertwig, 1879, Organism. d. Radiol., p. 88, Taf. ix. fig. 3, Taf. x. figs. 7-10.
Radial tubes cylindrical, straight, of nearly equal breadth throughout their whole length, somewhat inflated on the proximal basal end, smooth throughout the greater part of their length, but in the distal third dentate, with numerous (ten to forty) small pointed teeth, which are curved outwards, and shorter than the thickness of the tube.