Page:Scientific results HMS Challenger vol 18 part 2.djvu/432

1308 transverse rows of alternating square pores. Mouth little constricted, nearly as long as the thorax, with a narrow, prominent peristome.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.08 long, 0.05 broad.

Habitat.—Arctic Ocean, Greenland (Schaffner); Iceland (Krabbe).

11. Dictyocephalus ampulla, n. sp.

Shell thin-walled, smooth, with slight collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 3. Cephalis subspherical, without pores, hyaline. Thorax inflate, subspherical, with scarce and small, widely-scattered, circular pores. Mouth constricted, only one-third as broad as the thorax, with a narrow, prominent peristome.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.08 long, 0.07 broad.

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

Definition.—Mouth of the thorax flat or truncate, without prominent ring-like peristome.

12. Dictyocephalus obtusus, Ehrenberg.

Dictyocephalus obtusus, Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 830.

Lophophæna obtusa, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 40.

Cornutella obtusa, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 877.

Dictyocephalus obtusus, Haeckel, 1862, Monogr. d. Radiol., p. 296.

Shell smooth, thick-walled, with distinct collar stricture. Length of the two joints = 5 : 6, breadth = 4 : 5. Cephalis ovate, little smaller than the subcylindrical thorax. Pores subregular, circular, of little different sizes. Mouth truncate, without ring-like peristome.

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

Habitat.—Fossil in Tertiary rocks of Sicily (Caltanisetta), Grotte, &c.

13. Dictyocephalus globiceps, n. sp. (Pl. 62, fig. 7).

Shell rough, thin-walled, with distinct collar stricture. Length of the two joints = 6 : 8, breadth = 6 : 7. Cephalis subspherical, large, with circular, double-contoured pores. Thorax cylindrical, with irregular, roundish pores, the size of which, like the thickness of the wall, decreases gradually towards the truncate mouth, which has no ring-like peristome.

Dimensions.—Cephalis 0.06 long, 0.06 broad; thorax 0.08 long, 0.07 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.