Page:Scientific results HMS Challenger vol 18 part 2.djvu/224

1100 The genus Sphærospyris differs from all other in the regular spherical or spheroidal form of the lattice-shell. It may therefore be easily confounded with some species of the ; but the internal sagittal ring, placed in the median plane of the fenestrated sphere and connected with it by radial beams, leaves no doubt that it is derived from a true Spyroid, either Dictyospyris or Amphispyris, or another genus. Sometimes also four larger collar pores are visible.

1. Sphærospyris sphæra, Haeckel.

Dictyospyris sphæra, Bütschli, 1882, Zeitschr. f. wiss. Zool. vol. xxxvi. pp. 511, 539, Taf. xxxii. fig. 15, a, b.

Shell smooth, nearly spherical, slightly flattened at the base, with small regular circular pores. In the centre of the basal plate a regular rectangular cross with four equal collar pores.

Dimensions.—Diameter of the shell 0.11, of the enclosed ring 0.06.

Habitat.—Fossil in Barbados.

2. Sphærospyris quadriforis, n. sp.

Shell rough, nearly spherical, slightly flattened at the base, with small regular circular pores. In the centre of the basal plate a bilateral symmetrical cross with four ovate collar pores; two cardinal pores twice as large as the two jugular pores and six to eight times as broad as the other shell-pores.

Dimensions.—Diameter of the shell 0.26, of the enclosed ring 0.09.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

3. Sphærospyris globosa, n. sp. (Pl. 83, fig. 4).

Shell smooth, perfectly spherical, with small subregular circular pores. In the centre of the basal plate no larger collar pores. (The original collar pores are here of the same size as the other pores, and cannot therefore be distinguished.)

Dimensions.—Diameter of the shell 0.13, of the enclosed ring 0.06.

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

Definition.— with a discoidal, kidney-shaped, or subcircular shell, with a basal incision; without transverse constriction and free basal feet.

The genus Nephrospyris is one of the most peculiar and most modified of the, of extraordinary size, in this respect surpassing all other genera of this