Page:Scientific results HMS Challenger vol 18 part 1.djvu/861

Rh 11. Octopyle hexastyle, n. sp.

Cortical shell nearly rectangular, thorny, with six strong radial spines in the lateral plane, two opposite on the poles of the principal axis (prolongations of the principal beam at the sagittal septum), four others on the truncate corners of the quadrangular lateral girdle, which is one and a half times as long as broad. On the isthmus of the broad transverse girdle three pores. Sagittal septum longer than the hexagonal medullary shell. Eight egg-shaped gates.

Dimensions.—Length of the medullary shell 0.05, breadth 0.04; length of the cortical shell 0.18, breadth 0.12.

Habitat.—Northern Atlantic, surface; Canary Islands, Station 9, depth 3150 fathoms.

12. Octopyle sexangulata, n. sp. (Pl. 9, fig. 12).

Cortical shell thorny, hexagonal, with six strong conical radial spines on the six corners of the lateral girdle, lying in the lateral plane, two opposite on the poles of the transverse axis, four others in pairs on both sides of the annular sagittal constriction, which is only twice as long as the elliptical medullary shell. Transverse girdle broad, with five pores on the isthmus. Eight gates roundish, smaller than the medullary shell.

Dimensions.—Length of the medullary shell 0.045, breadth 0.035; length of the cortical shell 0.11, breadth 0.13.

Habitat.—Pacific, central area, Station 270, surface.

13. Octopyle octostyle, n. sp.

Cortical shell elliptical, thorny, with eight long cylindrical radial spines, lying in two crossed diagonal planes, opposite in pairs, quite as in the nearly related Tetrapyle octacantha. It differs from this species by the perfect, latticed, vertical sagittal septum, which divides every gate into two triangular halves. Lateral girdle elliptical, one and a third times as long as broad. Transverse girdle on the isthmus with three pores. Septum longer than the elliptical medullary shell.

Dimensions.—Length of the medullary shell 0.06, breadth 0.045; length of the cortical shell 0.16, breadth 0.12.

Habitat.—South Pacific, Station 288, surface.

14. Octopyle obtecta, n. sp.

Cortical shell quadrangular, thorny, with eight strong diagonal spines, lying in two crossed planes, and arising from the proximal edges of the gates in the same way as in the foregoing species. It differs from this by four prominent latticed roofs, which arise from the distal edge of the gates and connect the diagonal spines of one gate. Octopyle obtecta bears therefore the same relation to Octopyle octostyle that Tetrapyle pluteus does to Tetrapyle octacantha.

Dimensions.—Length of the medullary shell 0.055, breadth 0.04; length of the cortical shell 0.16, breadth 0.12.

Habitat.—Indian Ocean, surface, Madagascar, Rabbe.