2. Leptosphæra serrata, n. sp.
Inner shell with regular, hexagonal meshes, five to six times as broad as the bars; outer shell three times as broad, with simple triangular meshes. Radial spines with three serrated edges (of the same form as the main spines of Drymosphæra dendrophora, Pl. 20, fig. 1).
Dimensions.—Diameter of the outer shell 0.45, of the inner 0.15.
Habitat.—Central Pacific, Station 271, surface.
3. Leptosphæra polygonalis, n. sp.
Inner shell with irregular, polygonal meshes and very thin thread-like bars; outer shell twice as broad, with simple triangular meshes. Radial spines with three smooth edges. (Resembles Drymosphæra polygonalis, Pl. 19, fig. 1, but has no by-spines.)
Dimensions.—Diameter of the outer shell 0.35, inner 0.175.
Habitat.—North Pacific, Station 256, surface.
Subgenus 2. Leptosphæromma, Haeckel.
Definition.—Radial spines with three rows of lateral branches (one row on each edge).
4. Leptosphæra ciliata, n. sp.
Inner shell with regular, hexagonal meshes and very thin thread-like bars; outer shell three times as broad, with simple triangular meshes. Radial spines with smooth edges and three rows of simple, smooth, curved, lateral branches (six branches on each edge), similar to those of Diplosphæra gracilis.
Dimensions.—Diameter of the outer shell 0.6, inner 0.2.
Habitat.—South Atlantic, Station 325, surface.
5. Leptosphæra spinosa, Haeckel.
Inner shell with regular, hexagonal meshes, five times as broad as the bars; outer shell three times as broad, with simple triangular meshes. Radial spines with three densely serrated edges, and with three rows of serrated, simple, curved, lateral branches (three branches on each edge). Differs from the preceding in the thicker bars and the elegantly denticulated spines and branches.
Dimensions.—Diameter of the outer shell 0.66, inner 0.22.
Habitat.—Mediterranean (Messina), R. Hertwig.
6. Leptosphæra stellata, n. sp.
Inner shell with regular, hexagonal meshes, six times as broad as the bars, each bar crossed by a transverse tangential rod, so that each mesh represents an elegant six-rayed star (as
