Habitat.—North Pacific, Station 244, surface.
2. Diporaspis circopora, n. sp.
Shell with fifty-two sutures and one hundred to one hundred and fifty sutural pores, with four hexagonal and sixteen pentagonal plates. Both aspinal pores of each plate circular, very large, six to eight times as broad as the small circular sutural pores (in each suture two to three pores). Radial spines strongly compressed, two-edged; outer half shorter than the inner. By-spines undulate, half as long as the radius.
Dimensions.—Diameter of the shell 0.12, of the parmal pores 0.02 to 0.03, of the sutural pores 0.003 to 0.004.
Habitat.—South Pacific, Station 287, surface.
Subgenus 2. Diporaspidium, Haeckel.
Definition.—Shell with fifty-four sutures, four polar plates on each pole of the main axis different in pairs: two major hexagonal meeting in a polar ("geotomical") suture, two minor pentagonal, not meeting together (separated by that suture). Shell therefore composed of eight hexagonal plates (four equatorial and four polar) and of twelve hexagonal plates (eight tropical and four polar).
3. Diporaspis zygopora, n. sp.
Shell with fifty-four sutures and fifty-four circular sutural pores: with eight hexagonal and twelve pentagonal plates. Both aspinal pores of each plate elliptical, three times as broad as the sutural pores. Radial spines compressed, two-edged; outer half shorter than the inner. By-spines very numerous, simple, one-third as long as the radius, forming coronels or elegant circles around the pores (a small coronel around each sutural pore, a large one around each couple of aspinal pores).
This typical species is nearly allied to Dorataspis typica (Pl. [138], fig. 4), and may be derived from it by development of the coronels of by-spines.