Page:Scientific results HMS Challenger vol 18 part 2.djvu/166

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Definition.— with two simple lateral feet, forming a ring by union.

The genus Gamospyris and the similar Stephanospyris differ from all other in the possession of a large basal ring, placed in the frontal plane of the shell. This ring has been produced by concrescence of the distal ends of the two large curved lateral feet of Dipospyris.

1. Gamospyris circulus, n. sp. (Pl. 83, fig. 19).

Shell subspherical, tuberculate, with subregular circular pores. Basal plate with four larger collar pores. Apical horn pyramidal, about as long as the shell. The connected feet form together a circular or nearly circular smooth ring, the diameter of which is three to four times as great as that of the shell.

Dimensions.—Shell 0.08 long, 0.09 broad; diameter of the arm-ring 0.25 to 0.33.

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

2. Gamospyris annulus, n. sp.

Shell nut-shaped, tuberculate, with subregular circular pores. Basal plate with four large central and a circle of eight to twelve small peripheral pores. Apical horn conical, twice as long as the shell. The connected arms form together an elliptical smooth ring, which is five times as long and three times as broad as the shell.

Dimensions.—Shell 0.07 long, 0.09 broad; ring 0.33 long, 0.26 broad.

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

Definition.— with two lateral feet bearing a series of secondary spines and forming a ring by union.

The genus Stephanospyris exhibits the same peculiar armature of the semipinnate lateral feet as its ancestral genus Dorcadospyris, but differs from it in the concrescence of the distal ends of the feet, to form a complete foot-ring. The former therefore bears to the latter the same relation that Gamospyris does to Dipospyris.

1. Stephanospyris cordata, n. sp. (Pl. 85, fig. 10).

Shell subspherical, tuberculate, with small regular circular pores. Basal plate with four larger pores. Apical horn cylindrical, three times as long as the shell, with three to four verticils