Page:Scientific results HMS Challenger vol 18 part 1.djvu/456

248 Radial spines very strong, with dentated edges and with three rows of lateral branches (six dentated curved branches on each edge).

Dimensions.—Diameter of the outer shell 0.4, inner 0.13.

Habitat.—North Atlantic, Azores, surface.

7. Diplosphæra reticulata, n. sp.

Inner shell with regular, hexagonal meshes, five times as broad as the bars, which are densely covered with very numerous, simple bristle-shaped by-spines; outer shell four times as broad, with very numerous small irregular polygonal meshes, forming a very delicate network, and filling out the large triangular main meshes. Radial spines with three serrated edges and three rows of short curved branches (four to five branches on each edge).

Dimensions.—Diameter of the outer shell 0.6, inner 0.15.

Habitat.—North Atlantic, Gulf Stream, Færöe Channel, surface, John Murray.

8. Diplosphæra triglochin, n. sp.

Inner shell with irregular, polygonal meshes and very thin thread-like bars; outer shell three times as broad, with similar irregular polygonal meshes, filling out the large triangular main meshes. Radial spines with three serrated edges, each of which bears one single large lateral branch, concavely curved towards the distal end. By-spines of the inner shell very numerous.

Dimensions.—Diameter of the outer shell 0.5, inner 0.17.

Habitat.—Central Pacific, Station 264, surface.

Definition.— with two extracapsular cortical shells, connected by long prismatic, radial spines; outer shell with thin radial by-spines.

The genus Drymosphæra differs from its ancestral form Leptosphæra in the development of radial by-spines on the surface of the outer shell, the inner shell being smooth.

Definition.—Radial by-spines simple, not branched (main spines simple).

1. Drymosphæra hexagonalis, n. sp.

Inner shell with regular, hexagonal meshes and very thin thread-like bars; outer shell twice as broad, with simple triangular meshes and thin thread-like bars, which bear very numerous,