1738 THE VOYAGE OF H.M.S. CHALLENGER. 



1. Ccelodrymus ancoratus, n. sp. (PI. 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 O3 to 0'4 

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



2. Ccelodrymus 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. Ccelodrymus 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. 



Genus 730. Ccelodasea, 1 n. gen. 



Definition. Ccelodendrida with an external spongy lattice-mantle, produced by 

 the anastomosing branches of the hollow tubes, which are connected in different heights. 



The genus Ccelodasea differs from the preceding Ccelodrymus in the spongy structure 

 of the outer bivalved mantle. The hollow branches of the radial tubes of Ccelodendrum, 

 which anastomose in Ccelodrymus only on the spherical surface of the calymma, and form 

 a simple lattice-sphere, become connected in Ccelodasea 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 Carpo- 

 sphcera among the Sphseroidea. 



1 Ccelodasea = Hollow thicket, xoiAoj laata. 



