Page:Scientific results HMS Challenger vol 18 part 2.djvu/299

Rh 1. Phænoscenium hexapodium, n. sp. (Pl. 98, fig. 9).

Shell campanulate, smooth, about as long as broad. Network delicate, with irregular polygonal pores and thin bars. Columella with four to six ascending three-branched verticils, prolonged into the conical hollow apical horn (with six to eight smaller verticils) which is about as long as the shell. Six basal feet curved, divergent, of the same length, with pinnate middle rod.

Dimensions.—Shell 0.1 long, 0.11 broad; horn and feet 0.08 to 0.09 long.

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

2. Phænoscenium cladopodium, n. sp.

Shell campanulate, conical, smooth, somewhat broader than long. Network with irregular roundish pores, about as broad as the bars. Columella with a single verticil of three ascending branches. Horn pyramidal, stout, as long as the shell, with three dentate edges. Six feet divergent, slightly curved, very unequal; three primary (or perradial) very large, longer than the shell, three sided pyramidal, with three dentate edges; three secondary (or interradial) much smaller, simple, shorter than the shell.

Dimensions.—Shell 0.05 long, 0.06 broad; horn and feet 0.04 to 0.07 long.

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

3. Phænoscenium polypodium, n. sp.

Shell subspherical, about as long as broad, smooth. Network with regular circular pores, twice as broad as the bars. Columella with two verticils of three ascending branches, prolonged into a stout conical horn of twice the length. Twelve to fifteen conical curved divergent feet, about as long as the shell. The three primary feet are directly connected with the base of the columella.

Dimensions.—Shell 0.08 diameter, horn 0.15 long, feet 0.07 to 0.09 long.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Definition.— (vel Monocyrtida multiradiata clausa) with an apical horn and simple internal cavity of the shell without axial columella.

The genus Calpophæna and the following closely tied Archiphæna differ from the two preceding genera of Archiphænida in the simple shell cavity, which encloses no columella. They may be derived either from the preceding Phænocalpis by loss of the columella, or directly from the Zygospyrida by reduction of the sagittal constriction and loss of the primary ring. Different subgenera may be distinguished in Calpophæna according either to the number of the feet or to their shape (being simple or branched).