Definition.—Cœlodendrida 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 Sphæroidea.
1. Cœlodasea ramosissima, Haeckel.
Cœlodendrum ramosissimum (partim), Haeckel, 1862, Monogr. d. Radiol., p. 363, Taf. xiii. fig. 4.
Spongy framework of the spherical bivalved mantle very dense and thick, produced by very numerous, irregular anastomoses of the lateral and terminal branches, which arise from the hollow tubes. The last and thinnest terminal branches are forked, as seen in the radial section of fig. 4 (loc. cit.), their ends are closed and armed with some very small denticles (not open, as figured in fig. 4). In my Monograph I had confounded this species with Cœlodendrum ramosissimum, which however, may possibly be its ancestral form.
Dimensions.—Diameter of the spongy spherical mantle 2 to 2.5, of the central valves 0.15.
Habitat.—Mediterranean (Messina), surface.
2. Cœlodasea spongiosa, n. sp.
Spongy framework of the bivalved mantle rather loose, not nearly so thick and dense as in the preceding species. The last and thinnest terminal branches are prolonged into denticulate, zigzagged, radial filaments, which bear at their distal end an anchor with two recurved teeth (similar to Cœlodrymus ancoratus, Pl. [121], figs. 9, 10).
Dimensions.—Diameter of the spongy spherical mantle 3 to 3.2, of the central valves 0.24.