Gate elliptical. Ring pentagonal, with three prominent edges and five pairs of branched spines on the five corners. In each corner arise two or three curved spines, about as long as the radius of the gate, each with two to four forked branches. _Dimensions._--Diameter of the gate 0.08; length of the spines 0.03 to 0.05. _Habitat._--North Atlantic, Station 354, surface. 4. _Lithocircus hexablastus_, n. sp. (Pl. 81, fig. 17). Gate elliptical. Ring hexagonal, with three prominent edges and six pairs of branched spines, arising from the six corners. Each of the twelve spines is short and stout, only half as long as the radius of the gate, and bears a bunch of ten to twenty short, densely aggregated, conical or horn-like curved branches. _Dimensions._--Diameter of the gate 0.1; length of the spines 0.02 to 0.03. _Habitat._--Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms. 5. _Lithocircus crambessa_, n. sp. (Pl. 81, fig. 6). Gate elliptical or subcircular. Ring hexagonal, with three wing-shaped distorted edges and six groups of branched spines, arising from the six corners. In each corner arise three short and stout divergent spines, each bearing a bunch of numerous short roundish branches like a cauliflower, scarcely as long as the thickness of the ring. _Dimensions._--Diameter of the ring 0.1 to 0.12, length of the spines 0.01 to 0.02. _Habitat._--Western Tropical Pacific, Station 225, depth 4475 fathoms. 6. _Lithocircus tarandus_, n. sp. (Pl. 92, fig. 19). Gate circular. Ring hexagonal, with three sharp edges and six pairs of large branched spines, arising from the flat lateral edges on the six corners. Each of the twelve spines is horizontally expanded, longer than the diameter of the ring and dichotomously forked like the antlers of a {945}reindeer. If the lateral ends of the branches of this species become united in the frontal plane, we get _Microcubus_, the four upper spines forming the mitral ring, the four middle the equatorial ring, and the four lower the basal ring. _Dimensions_.--Diameter of the gate 0.08; length of the spines 0.09. _Habitat_.--Central Pacific, Station 272, surface. 7. _Lithocircus furcatus_, n. sp. Gate ovate. Ring ovate, with three sharp prominent edges. The two lateral edges are smooth. The median edge (in the sagittal plane) bears sixteen to twenty forked spines (commonly eight dorsal, eight ventral, and four basal). All the spines are of nearly equal size, slightly curved, and about half as long as the short sagittal axis of the ring. _Dimensions_.--Diameter of the gate 0.08 to 0.12; length of the spines 0.03 to 0.04. _Habitat_.--North Pacific, Station 253, depth 3125 fathoms. 8. _Lithocircus magnificus_, n. sp. (Pl. 81, fig. 16).