Habitat.—Central Pacific, Station 268, depth 2900 fathoms.
3. Oroplegma velatum, n. sp.
Radial spines stout, cylindrical, somewhat club-shaped, spiny, slightly curved, about three to four times as broad as the thorny bars of the network. External shell a simple lattice-sphere with irregular polygonal meshes, which are for the most part pentagonal and about four times as broad as the polygonal meshes of the inner shell. The free prominent parts of the radial spines are thickened, club-shaped, and about as long as the radius.
Dimensions.—Diameter of the inner sphere 2.0 to 2.4, of the outer 2.8 to 3.6; length of the free spines 0.5 to 0.7, breadth 0.12 to 0.15.
Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms.
Subgenus 2. Orodictyum, Haeckel.
Definition.—External shell a complex framework, forming an outer spongy envelope around the inner primary shell.
4. Oroplegma spongiosum, n. sp. (Pl. [107], fig. 3).
Radial spines stout, cylindrical, spinulate, slightly curved, three to five times as broad as the inner rough bars. External shell with pyramidal elevations, forming a loose spongy framework, the irregular polygonal meshes of which are two to five times as broad as those of the enclosed internal shell; the thickness of the spongy envelope equals about half the radius of the inner shell. External free prolongations of the radial spines about equal to the radius.
Dimensions.—Diameter of the inner sphere 2 to 2.5, of the outer 3 to 3.5; length of the free radial spines 0.5 to 2.0, breadth 0.1.