Page:Scientific results HMS Challenger vol 18 part 2.djvu/167

Rh of teeth. The connected feet form a heart-shaped ring, four times as long and three times as broad as the shell. Each foot bears on the outer convex edge four to six stout conical teeth, shorter than the shell. Distal ends crossed and prominent.

Dimensions.—Shell diameter 0.1; length of the arm-ring 0.4, breadth 0.3.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

2. Stephanospyris verticillata, n. sp. (Pl. 85, fig. 11).

Shell nut-shaped, tuberculate, with subregular circular pores. Basal plate with numerous small pores. Apical horn cylindrical, four to six times as long as the shell, with six to ten verticils of teeth. The connected feet form a circular ring, the diameter of which is four times as great as that of the shell. Each foot bears ten to twelve conical teeth, about as long as the shell. Distal ends not crossed and not prominent.

Dimensions.—Diameter of the shell 0.1, of the arm-ring 0.4.

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

3. Stephanospyris excellens, n. sp. (Pl. 83, fig. 20).

Shell subspherical, tuberculate, with regular circular pores. Basal plate with numerous small pores. Apical horn cylindrical, twice as long as the shell, with eight verticils of teeth. The connected feet form an ovate ring, which is three times as long and two and a half times as broad as the shell. Each foot bears eight conical spinulate teeth, about as long as the shell. The crossed and prominent distal ends bear two parallel vertical teeth.

Dimensions.—Diameter of the shell 0.1, of the arm-ring 0.2 to 0.3.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Definition.— tetrapoda, with four descending basal feet, two of which are opposite in the sagittal plane (an odd caudal and an odd sternal foot), whilst the two others are paired lateral or pectoral feet.

Definition.— with four basal feet crossed in pairs (two sagittal and two lateral). Apex with a horn.

The genus Tetraspyris and the following closely allied Tessarospyris represent together the small subfamily of Tetraspyrida, characterised by the possession of four descending basal feet, three of which correspond to the three original feet of the