Page:Scientific results HMS Challenger vol 18 part 1.djvu/602

394 irregular, roundish pores, once to five times as broad as the bars. On the base of each distal chamber (beginning in the second or third pair) a circle of twelve to sixteen larger square pores. Both medullary shells compressed lenticular. (Resembles the inner cortical shell of Desmartus larvalis, Pl. 40, fig. 12, but is without the polar tubes and the outer envelope of this species.)

Dimensions.—Length of the six-chambered cortical shell 0.23; greatest breadth of each chamber 0.07; pores 0.002 to 0.01, bars 0.002.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific, in various depths.

Definition.—Surface of the cortical shell thorny or spiny, but without peculiar polar spines and without regular coronals of spines.

4. Ommatocampe erucæformis, n. sp.

Cortical shell with spiny surface, composed of six to twelve chambers of nearly the same size and form, the distal chambers a little smaller. The form and structure of the cortical shell is nearly the same as in the foregoing species, only the pores are somewhat larger, and the whole surface is covered with bristle-like radial spines, about half as long as the breadth of one chamber. Both medullary shells compressed and lenticular.

Dimensions.—Length of the six-chambered cortical shell 0.24; greatest breadth of each chamber 0.08; pores 0.005 to 0.012, bars 0.002.

Habitat.—North Atlantic, Canary Islands, Station 353, depth 2965 fathoms.

5. Ommatocampe nereis, n. sp. (Pl. 40, fig. 10).

Cortical shell with spiny surface, composed of six (or more) chambers of different size and structure. Both proximal chambers kidney-shaped, with subregular, circular, hexagonally framed pores, twice as broad as the bars. All following chambers cap-like, with much smaller, irregular, roundish pores, at the base of every chamber a circle of ten to twelve large square pores. Spines of the surface short, irregularly scattered. Both medullary shells spherical. (All the observed specimens possessed only six chambers.)

Dimensions.—Length of the six-chambered cortical shell 0.25; greatest breadth of each chamber 0.08; pores of both proximal chambers 0.01, bars 0.005; basal pores of the other chambers 0.02; pores of their distal caps 0.003 to 0.006, bars 0.003.

Habitat.—Pacific, central area, Stations 271 to 274, depth 2350 to 2750 fathoms.

Definition.—Surface of the cortical shell spiny, on every chamber a regular circle or coronal of radial spines.