Page:Scientific results HMS Challenger vol 18 part 2.djvu/160

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Definition.— with two simple free basal feet and one apical horn.

The genus Dipospyris and the following five genera represent together the interesting subfamily of Dipospyrida, which always bear two opposite lateral feet only. Therefore in this bipedal group the biradial or bilateral type of the is particularly expressed. Such bipedal forms never occur in the. The topographical relation of the two lateral feet to the rods of the collar-plate, and to the cortinar pores separated by these, leaves no doubt that they correspond to the pectoral feet of Cortina and Tripospyris, and therefore that the Dipospyrida have originated from the Tripospyrida by loss of the caudal foot. Dipospyris is the simplest form of the Dipospyrida, with two simple free feet.

1. Dipospyris bipes, n. sp.

Shell thorax-shaped, smooth, with deep sagittal stricture, two vaulted bosoms, and subregular circular pores. Basal plate with two large collar pores only. Horn and feet equal, conical, straight, about as long as the shell; the feet widely divergent.

Dimensions.—Shell 0.08 long, 0.12 broad; horn and feet 0.1 to 0.15 long.

Habitat.—Fossil in Barbados.

2. Dipospyris mystax, Haeckel.

Ceratospyris mystax, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xx. fig. 6.

Shell elliptical spinulate, with slight collar stricture and large subregular circular pores. Basal plate with three pores (?) Horn small conical, oblique, shorter than the shell. Feet slender conical, longer than the shell, slightly curved, divergent. At the base of the columella, between the two feet, a small rudiment of the last caudal foot is visible.

Dimensions.—Shell 0.06 long, 0.1 broad; horn 0.02, feet 0.12 long.

Habitat.—Fossil in Barbados.

3. Dipospyris cubus, n. sp. (Pl. 83, fig. 18).

Shell box-shaped, subcubical, papillate, without external sagittal stricture, with numerous subregular circular pores. Basal plate with three very large collar pores, surrounded by a circle of smaller pores. Apical horn short and thick, scarcely half as long as the shell. Feet of the same form, longer than the shell, widely divergent.

Dimensions.—Shell 0.08 long, 0.11 broad; horn 0.03 long, feet 0.14 long.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.