Subgenus 1. Clathrocanidium, Haeckel.
Definition.—Horn of the cephalis simple, not fenestrated. Peristome smooth.
1. Clathrocanium squarrosum, Ehrenberg.
Clathrocanium squarrosum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. vii. fig. 5.
Cephalis campanulate, with irregular roundish pores and a pyramidal horn of the same length, bearing at the apex three short branches. Length of the two joints 2 : 3, breadth = 2 : 6. Thorax with three simple, prismatic, thin ribs, which are twice as long as the cephalis, separated by large triangular holes and connected only at the distal end by a small triangular ring of delicate lattice-work. Peristome smooth, wide, as broad as the thorax.
Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.06 long, 0.12 broad.
Habitat.—Western Tropical Pacific (Philippine Sea), depth 3300 fathoms.
2. Clathrocanium sphærocephalum, n. sp. (Pl. [64], fig. 1).
Cephalis spherical, with regular circular pores and a prismatic horn of the same length, with three serrated edges. Length of the two joints = 2 : 3, breadth 2 : 4. Thorax with three broad, triangular, latticed, divergent ribs, which are separated by three large ovate holes (about as large as the cephalis), and connected at the distal end by a broad fenestrated circular ring of regular lattice-work (about six pores in its height). Peristome smooth, constricted, half as broad as the thorax.
Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.06 long, 0.08 broad.