Radial spines quadrangular, thin; their outer pyramidal part shorter than the inner. Each spine with four branches, its two opposite apophyses being simply forked. The eighty condyles (or sutural ends of the branches) much thickened, twice to four times as broad as the branches themselves. Network with forty sutures and twenty-two large meshes, as in both foregoing species.
Dimensions.—Diameter of the shell 0.12, of the meshes 0.03 to 0.04; breadth of the condyles 0.01.
Habitat.—South Pacific, Station 288, surface.
4. Phractaspis bipennis, Haeckel.
Dorataspis bipennis, Haeckel, 1862, Monogr. d. Radiol., p. 413, Taf. xxi. figs. 1, 2.
Phractasplenium bipenne, Haeckel, 1882, Manuscript.
Radial spines very thin, quadrangular; their outer pyramidal part shorter than the inner. Each spine with four bent branches, its two opposite apophyses being simply forked. Eighty condyles, very thin, pointed. In the specimens of this remarkable species, which I first observed in Messina, two opposite equatorial spines had quite free apophyses, not connected with the neighbouring spines; therefore the thin lattice-work of the shell exhibited only thirty-six sutures and twenty meshes (two meshes with six sutures, six meshes with four sutures, and twelve meshes with three sutures). In similar specimens, which I afterwards observed in the Canary Islands, all four equatorial spines were connected in the same manner with the neighbouring spines; therefore they possessed forty sutures and twenty-two meshes, like Phractaspis prototypus (Pl. [137], fig. 2). Perhaps the Mediterranean species represents a peculiar genus, Phractasplenium bipenne.
Dimensions.—Diameter of the shell 0.1, of the meshes 0.03 to 0.05; breadth of the spines 0.002.
Habitat.—Mediterranean (Messina), Canary Islands (Lanzerote), surface.