Page:Scientific results HMS Challenger vol 18 part 2.djvu/478

1354 as large as the thoracic pores. Feet nearly vertical, only slightly divergent, S-shaped, bent, as long as the abdomen, cylindrical; at the distal end shovel-shaped and fenestrated (often much more than in Ehrenberg's figure).

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.1; breadth, a 0.03, b 0.09, c 0.15.

Habitat.—Fossil in Barbados.

5. Dictyopodium thyrsolophus, n. sp. (Pl. 73, fig. 7).

Shell subconical, rough, with two slight strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 6. Cephalis hemispherical, with an elegant horn, which is half as long as the shell, spindle-shaped and scaly on the distal third. Thorax hemispherical, with small, regular, circular pores. Abdomen inflated, papillate, with regular, circular pores, three times as large as the thoracic pores (five to six in the course of its length). Feet slightly divergent, cylindrical, about as long as the shell, shovel-shaped and fenestrated (with a prominent middle rib) at the distal end.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.12; breadth, a 0.04, b 0.1, c 0.18.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Definition.— with the basal mouth of the shell fenestrated (vel Tricyrtida triradiata clausa).

Definition.— (vel Tricyrtida triradiata clausa) with three solid lateral wings on the thorax.

The genus Lithornithium has an ovate or spindle-shaped shell, with two distinct strictures, and tapering towards both poles. The abdomen is simple, whilst the cephalis bears an apical horn, and the thorax three free, lateral, solid, divergent wings. It may be derived from Pterocorys by development of a terminal lattice-plate closing the mouth.

1. Lithornithium ciconia, n. sp. (Pl. 67, fig. 3).

Shell nearly spindle-shaped, with two indistinct strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 3. Cephalis ovate, with a large pyramidal spine of twice the length. Thorax three-sided pyramidal with three pyramidal wings of the same length, the broad triangular bases of which occupy the whole length of the thoracic edges. Abdomen inversely ovate (in the