Page:Scientific results HMS Challenger vol 18 part 2.djvu/862

1738 1. Cœlodrymus ancoratus, n. sp. (Pl. 121, figs. 9, 10).

Network of the mantle loose, with large, irregular, polygonal meshes; the terminal branches of the forked trees, which communicate at the spherical surface of the calymma, and compose the mantle, are smooth. Spherical surface covered with very numerous and thin zigzag radial filaments, which are about as long as the galea, and bear at the distal end an anchor with two recurved teeth, denticulate at the concave proximal edge (fig. 10).

Dimensions.—Diameter of the spherical lattice-mantle 2 to 2.5, of the valves 0.3 to 0.4.

Habitat.—South-Eastern Pacific (off Juan Fernandez), Station 300, depth 1375 fathoms.

2. Cœlodrymus lappulatus, n. sp.

Network of the mantle rather dense, with numerous and small irregular polygonal meshes; the terminal branches of the forked trees, which compose the mantle, are spinulate. Spherical surface densely studded with very numerous spinulate, radial filaments, which are about half as long as the galea, and bear at the distal end an anchor with four crossed recurved teeth, denticulate at the concave proximal edge.

Dimensions.—Diameter of the spherical lattice-mantle 2.5 to 3, of the valves 0.4 to 0.5.

Habitat.—South-Western Pacific (east of New Zealand), Station 169, depth 700 fathoms.

3. Cœlodrymus echinatus, n. sp.

Network of the mantle very dense, with very numerous and small irregular roundish meshes; the terminal branches of the forked trees, which compose the mantle, are spiny. Spherical surface studded with very numerous, thin, radial bristles, which bear no anchor at the distal end.

Dimensions.—Diameter of the spherical lattice-mantle 1.8, of the valves 0.22.

Habitat.—South Pacific, Station 289, depth 2550 fathoms.

Definition.— with an external spongy lattice-mantle, produced by the anastomosing branches of the hollow tubes, which are connected in different heights.

The genus Cœlodasea differs from the preceding Cœlodrymus in the spongy structure of the outer bivalved mantle. The hollow branches of the radial tubes of Cœlodendrum, which anastomose in Cœlodrymus only on the spherical surface of the calymma, and form a simple lattice-sphere, become connected in Cœlodasea in different planes (laterally and terminally), and therefore form an irregular spongy framework. The latter exhibits therefore to the former a relation similar to that which Spongoplegma bears to Carposphæra among the.