Habitat.—Western Tropical Pacific, Station 224, depth 1850 fathoms.
2. Trissocircus binellipsis, n. sp. (Pl. [83], fig. 6).
Sagittal ring circular, smaller than the other two rings, which are both equal, elliptical, slightly constricted on the poles of the principal and transverse axes. The axis of the circular sagittal ring is the shorter axis of the frontal and equatorial ring, and about half as long as their longer axis. All three rings smooth, without spines.
Dimensions.—Height of the frontal ring 0.08, breadth 0.12.
Habitat.—Central Pacific, Station 268, depth 2900 fathoms.
3. Trissocircus octostoma (Pl. [93], fig. 11).
Sagittal ring circular, smaller than the other two rings, which are both equal, elliptical, distinctly constricted at the poles of the principal and transverse axes. The axis of the circular sagittal ring is the shorter axis of the frontal and equatorial ring, about one-third shorter than their longer axis. All three rings armed with short, irregularly branched spines.
Dimensions.—Height of the frontal ring 0.1, breadth 0.12.
Habitat.—Indian Ocean, Ceylon (Belligemma), Haeckel, surface.