Page:Scientific results HMS Challenger vol 18 part 2.djvu/331

Rh 11. Lithomelissa haeckelii, Bütschli.

Lithomelissa haeckelii, Bütschli, 1883, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 517, Taf. xxxiii. fig. 23, a, b.

Shell rough, with sharp collar stricture. Relative length of the two joints = 6 : 5, breadth = 6 : 7. Cephalis subspherical, large, with two divergent horns, a very large, oblique pyramidal occipital horn on the summit, and a very small frontal horn on the middle of the forehead. Thorax campanulate, little larger than the cephalis, with regular circular pores of twice the breadth. From the upper part of the thorax, below the collar stricture, there arise three stout, divergent, angular, semi-lunar feet, about as long as the shell. Mouth wide open, not constricted.

Dimensions.—Cephalis 0.6 long, 0.6 broad; thorax 0.05 long, 0.07 broad.

Habitat.—Tropical Atlantic, Station 347, depth 2260 fathoms; fossil in Barbados.

12. Lithomelissa bütschlii, n. sp. (Pl. 56, fig. 1).

Shell smooth, with slight collar stricture. Relative length of the two joints = 5 : 6, breadth = 4 : 5. Cephalis ovate, large, with two small conical horns, which are opposed nearly horizontally, in the upper part of the cephalis; an anterior frontal and a posterior occipital horn. Thorax ovate, truncate, little larger. Pores of both joints irregular, roundish, of very different sizes. From the middle part of the thorax there arise three short conical divergent feet. (In the figured specimen there were some accessory thorns; in another specimen, found afterwards, the surface was quite smooth, but the two horns and the three feet much larger, half as long as the cephalis.)

Dimensions.—Cephalis 0.05 long, 0.04 broad; 0.06 long, 0.05 broad.

Habitat.—Central Pacific, Stations 266 to 274, depth 2350 to 2925 fathoms.

Definition.—Cephalis with three, four, or more horns, a primary occipital, a secondary frontal, and one or more accessory parietal horns.

13. Lithomelissa corythium, Ehrenberg.

Lithomelissa corythium, Ehrenberg, 1875, Abhandl. d.k. Akad. d. Wiss. Berlin, p. 78, Taf. iii, fig. 12.

Shell smooth, with slight collar stricture. Relative length of the two joints = 4 : 3, breadth = 4 : 5. Cephalis campanulate, with three short conical horns on the summit. Thorax flat and wide. From its upper part below the collar stricture, there arise three divergent, pyramidal feet, fenestrated at the base, about as long as the shell. Mouth wide open. (The specimen figured by Ehrenberg was an incomplete one.)

Dimensions.—Cephalis 0.04 in diameter, thorax 0.03 long, 0.05 broad.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; fossil in Barbados.