Page:Scientific results HMS Challenger vol 18 part 2.djvu/427

Rh with from two to four transverse rows of small, circular pores only. Mouth constricted, with a large cylindrical, tubular, hyaline peristome, half as long as the shell.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.09 long, 0.07 broad.

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

Definition.— (vel Dicyrtida eradiata aperta) with ovate or subcylindrical thorax, the mouth of which is either truncate or constricted. Cephalis armed with several large horns.

The genus Lophophæna differs from the nearly allied Sethocorys and Dictyocephalus only in the armature of the large cephalis, which bears a group of large horns, often arranged in a corona of radial spines. Sometimes these spines are connected by anastomosing branches (like Arachnocorys).

Definition.—Horns of the cephalis simple, free, radial spines, neither branched nor connected.

1. Lophophæna galea, Ehrenberg.

Lophophæna galea orci, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin p. 245.

Lophophæna apiculata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 11.

? Cornutella spiniceps, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. ii. fig. 6.

Shell with slight collar stricture. Length of the two joints = 5 : 4, breadth = 5 : 6. Cephalis subglobular, with numerous bristle-shaped, radial spines, about as long as its radius. Thorax about the same size, truncate, conical, smooth, with wide open mouth. Pores in both joints of equal size, small, regular, circular.

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

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms; also fossil in Barbados.

3. Lophophæna radians, Ehrenberg.

Lophophæna radians, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 9.

? Lophophæna lynx, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 13.

Shell with slight collar stricture. Length of the two joints = 4 : 6, breadth = 4 : 5. Cephalis subglobular, with numerous, stout, conical, radial spines, about as long as its diameter. Thorax