Page:Scientific results HMS Challenger vol 18 part 2.djvu/545

Rh The genus Lophocorys differs from its ancestral form, Theocorys, only in the armature of the cephalis, bearing either two divergent horns, or a corona of several radial horns. In two species there are four horns on the apex, a larger vertical (occipital) horn being surrounded by three smaller, upwards divergent horns.

1. Lophocorys astrocephala, n. sp. (Pl. 69, fig. 9).

Shell smooth, inversely ovate, with deep collar and slight lumbar stricture. Length of the three joints = 3 : 7 : 6, breadth = 4 : 11 : 10. Cephalis subspherical, stellate, densely covered with numerous (ten to twenty or more) divergent, large, slenderly conical horns, the longest of which reach the length of the shell. Thorax campanulate, with small, regular, circular pores. Abdomen tapering towards the constricted mouth, in the upper half with the same pores, in the lower half with smaller, scarce pores, or nearly hyaline.

Dimensions.—Length of the three joints, a 0.03, b 0.07, c 0.06; breadth, a 0.04, b 0.11, c 0.1.

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

2. Lophocorys acanthocephala, Haeckel.

Eucyrtidium acanthocephalum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. ix. fig. 8.

Shell rough, bottle-shaped, with two slight strictures. Length of the three joints = 5 : 11 : 7, breadth = 4 : 12 : 10. Cephalis conical, with a large pyramidal horn of the same length, and three smaller divergent accessory horns at the base of the three edges of the latter. Thorax campanulate, nearly as long as the tapering abdomen (which in the figure of Ehrenberg is broken off). Pores regular, circular, quincuncial.

Dimensions.—Length of the three joints, a 0.05, b 0.11, c 0.07; breadth, a 0.04, b 0.12, c 0.1.

Habitat.—Fossil in Barbados.

3. Lophocorys bicornis, Haeckel.

Eucyrtidium bicorne, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 7.

Shell smooth, almost spindle-shaped, with two slight strictures. Length of the three joints = 2 : 8 : 3, breadth = 3 : 5 : 4. Cephalis hemispherical, with two stout, pyramidal, divergent horns of twice the length. Thorax ovate, with seven to eleven transverse rows of small, regular, circular pores (often very scarce in the upper half). Abdomen with two to four transverse rows of the same pores. Mouth constricted, half as broad as the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.03; breadth, a 0.03, b 0.05, c 0.04.

Habitat.—Fossil in Barbados.