Page:Scientific results HMS Challenger vol 18 part 2.djvu/275

Rh widely divergent, straight, twice as long as the shell-diameter. Three lateral wings broad, each with a basal row of few very large irregular roundish meshes, and several distal rows of small square meshes. This species is very similar to Clathrocorys murrayi (Pl. 64, fig. 8), but has no trace of thorax-wall. The latter species may be derived from the former by development of the thoracic lattice, which connects the three free feet.

Dimensions.—Shell 0.05 long, 0.06 broad.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

3. Archiscenium tripterygium, n. sp.

Shell hemispherical, smooth, with numerous irregular roundish meshes of very different sizes. Basal lattice with four large meshes, two major cardinal and two minor cardinal pores. Apical horn and the three feet of similar form and size, slender prismatic, three to four times as long as the shell; the horn straight, the feet curved. Three lateral wings very delicate, with a basal row of few large irregular polygonal meshes, and several distal rows of similar small pores.

Dimensions.—Shell 0.04 long, 0.05 broad.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

4. Archiscenium cyclopterum, n. sp. (Pl. 98, fig. 3).

Shell hemispherical, with small irregular roundish pores. Basal lattice with four large meshes, two major cardinal and two minor jugular pores. Apical horn and the three feet of similar form and size, slender prismatic, straight, twice to four times as long as the shell. Three lateral wings nearly semicircular, densely latticed, with the same pores as the shell, and smooth convex margin.

Dimensions.—Shell 0.05 long, 0.06 broad.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

5. Archiscenium callimitra, n. sp.

Shell campanulate, with irregular polygonal pores. Basal lattice with nine meshes (three larger central and six smaller distal pores, as in Callimitra carolotæ, Pl. 63, fig. 8). Apical horn straight, prismatic, slender, conical, twice as long as the shell. Feet longer and more slender, slightly curved. Three lateral wings very broad, densely fenestrated, with irregular polygonal pores of the same shape as in the similar Callimitra carolotæ (Pl. 63, fig. 1).

Dimensions.—Shell 0.05 long, 0.04 broad.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Definition.— (vel Monocyrtida triradiata clausa) with a free branched internal columella, prolonged into an apical horn. Three basal feet connected with the horn by three vertical lateral wings.