Page:Scientific results HMS Challenger vol 18 part 2.djvu/285

Rh 7. Bathropyramis ramosa, n. sp. (Pl. 54, fig. 4).

Shell spiny, slenderly pyramidal, with three cortinar pores at the apex, and with nine (or sometimes eight or ten) strong radial beams, connected by fifteen to eighteen complete parallel rings. Meshes subregular, square, increasing gradually in size. Surface covered with forked or irregularly branched spines, arising from the nodal points.

Dimensions.—Shell 0.3 long, 0.17 broad.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

Definition.— (vel Monocyrtida multiradiata aperta) with simple, slender, pyramidal shell, and numerous radial beams (six to nine or more). Network double, with a delicate arachnoidal fenestration, filling up the large quadrangular meshes.

The genus Cinclopyramis differs from the preceding Bathropyramis in the development of a very delicate secondary network, filling up the large quadrangular meshes, which are produced by the crossing of the radial beams and the parallel horizontal rings. It therefore bears the same relation to the preceding genus that Plectopyramis does to Sethopyramis; it is perhaps derived directly from the former by loss of the small cephalis.

1. Cinclopyramis cribellum, n. sp.

Cinclopyramis cribellum = "Ladder of lattice-shape," Bury, 1862, Polycystins of Barbados, pl. xii. fig. 6.

Shell slender, pyramidal, with six strong radial ribs, which are connected by twelve to sixteen complete horizontal rings. Meshes trapezoidal, filled up by a very delicate and regular secondary network with square porules (two to four horizontal threads in each larger mesh).

Dimensions.—Shell 0.2 to 0.3 long, 0.12 to 0.16 broad.

Habitat.—Fossil in Barbados.

2. Cinclopyramis infundibulum, n. sp. (Pl. 54, fig. 7).

Shell slender, pyramidal, with nine strong radial ribs, which are connected by eighteen to twenty-four complete horizontal rings. Meshes subregular square, filled up by a very delicate and regular secondary network with square porules (ten to twelve horizontal threads in each larger mesh). Apex of the pyramid with three very small cortinar pores.

Dimensions.—Shell 0.3 to 0.4 long, 0.2 to 0.25 broad.

Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms.