Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.15; breadth, a 0.04, b 0.09, c 0.15.
Habitat.—South Atlantic, Station 338, depth 1990 fathoms.
18. Theocorys minervæ, n. sp. (Pl. [69], fig. 14).
Shell ovate, conical, with two deep strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 5. Cephalis subspherical, with a large pyramidal horn as long as the thorax, and with small, circular pores. Thorax rough, with regular, quincuncial, circular pores, three to four times as large as those of the cephalis. Abdomen barrel-shaped, with irregular, roundish pores of very different sizes, six very large pores immediately beyond the lumbar stricture, and four to five rows of pores, which are twice to four times as large as those of the thorax. Mouth truncated, with thickened margin, two-thirds as broad as the abdomen.
Dimensions.—Length of the three joints, a 0.04, b 0.12, c 0.16; breadth, a 0.04, b 0.16, c 0.2.
Habitat.—Central Pacific, Station 268, depth 2900 fathoms.
Genus 620. Axocorys,[[237]] Haeckel, 1881, Prodromus, p. 434.
Definition.—Theocorida (vel Tricyrtida eradiata aperta), with ovate abdomen, including an internal vertical axial rod, which bears three divergent radial spines or verticils of three branches, and is prolonged into an apical horn.
The genus Axocorys contains only a single but very remarkable species, and may, perhaps, represent a peculiar group, which has closer relations to the Plectoidea than to the other Tricyrtida. The pyriform three-jointed shell has neither lateral nor terminal free appendages, but possesses a very large apical horn, and an inner prolongation of this, an axial rod, which bears some triradiate verticils of branched spines. The original ancestral forms of this remarkable genus are probably Plagoniscus and Plectaniscus (pp. [912] and [924]).
1. Axocorys macroceros, n. sp. (Pl. [68], figs. 1, 1a).