Subgenus 2. Pristodiscus, Haeckel.
Definition.—Bases of the marginal spines connected by a solid siliceous equatorial girdle.
6. Trochodiscus stellaris, n. sp. (Pl. [48], fig. 3).
Disk with smooth surface. Pores subregular, circular; seven to eight on the radius. Marginal spines twelve to sixteen, triangular, of subregular size and disposition, about half as long as the radius of the disk, connected at their broad base by a solid equatorial girdle of half the breadth; girdle and spines radially striped.
Dimensions.—Diameter of the disk 0.25, of the pores 0.015; length of the spines 0.04 to 0.06, basal breadth 0.02 to 0.04.
Habitat.—Central Pacific, Station 268, depth 2900 fathoms.
7. Trochodiscus cingillum, n. sp.
Disk with smooth surface, in the distal part radially sulcated. Pores regular, circular; twelve to thirteen on the radius. Marginal spines twenty to twenty-four, triangular, of equal size and at regular distances, only one-fourth as long as the radius of the disk, connected at their broad base by a solid equatorial girdle of the double breadth. (Similar to Heliodiscus cingillum, Pl. [33], fig. 7, but without medullary shell.)
Dimensions.—Diameter of the disk 0.22, of the pores 0.004; length of the spines 0.02, basal breadth 0.02
Habitat.—South Pacific, Station 285, depth 2375 fathoms.