Page:Scientific results HMS Challenger vol 18 part 2.djvu/296

1172 5. Carpocanistrum evacuatum, n. sp. (Pl. 52, fig. 11).

Shell urceolate, smooth, thin-walled, one and a half times as long as broad. Pores regular circular, sixteen to twenty on the greatest breadth of the shell. Peristome slightly constricted, with twenty to twenty-five small triangular vertical feet.

Dimensions.—Shell 0.1 long, 0.07 broad; mouth 0.05 broad.

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

6. Carpocanistrum pyriforme, Haeckel.

Lithocarpium pyriforme, Stöhr, 1880, Palæontogr., vol. xxvi. p. 97, Taf. iii. fig. 10.

Shell pear-shaped or subspherical, one and a fourth times as long as broad. Pores roundish, polygonally framed (or with square meshes ?). Peristome strongly constricted, one-fourth as broad as the shell, somewhat tubular, with twelve to twenty short vertical and parallel feet. The position of this species is doubtful; perhaps it represents a peculiar genus.

Dimensions.—Shell 0.17 long, 0.14 broad; mouth 0.035 broad.

Habitat.—Fossil in Tertiary rocks of Sicily (Grotte) Stöhr.

Definition.— (vel Monocyrtida multiradiata aperta) with an ellipsoidal or nearly spherical double shell; outer shell arachnoidal or spongy. Peristome small, constricted with a corona of numerous radial feet. No apical horn.

The genus Arachnocalpis differs from the other Archiphormida by possessing a double shell (like Peripyramis). The large shell, reaching nearly half a millimeter in length is either ellipsoidal or nearly spherical, and composed of an inner primary and an outer secondary shell. Its network is very delicate, in the outer envelope either spongy or arachnoidal. This very remarkable genus has probably no true relation to the other Archiphormida but has been derived from true (Mitrocalpis) by development of a corona around the mouth.

1. Arachnocalpis ellipsoides, n. sp. (Pl. 98, fig. 13).

Shell ellipsoidal, one and a half times as long as broad, on the apical pole hemispherical, on the basal pole coronate, with an elegant prominent funnel-shaped peristome, which is one-eighth as broad as the shell, fenestrated by very fine pores, and bears fifteen to twenty short conical divergent teeth. Inner shell with irregular polygonal meshes of very different size, separated by thin,