1. Clathrocanium squarrosum, Ehrenberg.
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.
Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.
3. Clathrocanium coarctatum, Ehrenberg.
Cephalis spherical, thorny, with regular circular pores and a simple pyramidal horn of the same length. Length of the two joints = 2 : 3, breadth = 2 : 5. Thorax with three simple, prismatic, little prominent ribs, which are separated by three large ovate holes (twice as long as the cephalis), and connected below the prominent distal end by a narrow circular ring of delicate lattice-work. Peristome smooth, wide, little narrower than the thorax.
Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.06 long, 0.1 broad.
Habitat.—Western Tropical Pacific (Philippine Sea), depth 3300 fathoms.
4. Clathrocanium triomma, n. sp. (Pl. 64, fig. 3).
Cephalis spherical, thorny, with regular circular pores, and a slender prismatic horn of twice the length, bearing at its apex three short recurved branches. Length of the two joints = 2 : 4, breadth = 2 : 5. Thorax with three broad prismatic, fenestrated ribs, which are separated by three large sub-
