COCIILODESMA. 237 



zontal spoon-shaped lamina, which projects with a forward 

 inchnation from the posterior hinge-margin, npon which it 

 is entirely seated, and is strengthened there by a callosity 

 running between the beaks and the hinder muscular im- 

 pression. The umbonal cavities, from the front edge of 

 the lamina being unattached, and the dorsal edge being 

 simple and not margined, are exposed even to the tip of the 

 beaks. The ossicle, which forms a small segment of a 

 circle, is moderately convex on one side, and excavated in 

 the middle of the other. 



We had always regarded this as one of the rarest of our 

 British bivalves, since, although not confined to one or two 

 localities, it was no where obtained in any abundance, a 

 specimen or two being the average fruit of a season's 

 dredging. We learn, however, from a recent publication 

 of Professor Macgillivray's, that it is not unfrequently 

 brought up by the fishing-lines from deep water oiF Aber- 

 deen, and of dimensions (nearly an inch and a half long 

 and an inch broad) far above the average of English ex- 

 amples. "It is not uncommonly dredged from Falmouth 

 Harbour, but mostly single valves ; is also found on the 

 south coast of Devon, where we have taken perfect shells " 

 (Mont.). Dr. Pulteney procured it on the coast between 

 Weymouth and Portland, and on the north shore near 

 Brownsea Isle, Dorsetshire. Exmouth (Clark) ; Torbay, 

 Falmouth (Jeffreys) ; Penzance, in twenty-five fathoms 

 (M'Andrew and E. F.). It is obtained, though rarely, at 

 Scarborough (Bean) ; at Newbiggin in Northumberland 

 (Alder); the Isle of Man (M'Andrew and E. F.). " It is 

 rather a scarce species on the Irish Coast ; found at Magil- 

 ligan, Dublin, and Cork Coasts " (Thompson) ; at Kenmare 

 River, in Kerry (Jeff, cab.) ; Coast of Down (Patterson) ; 

 Bantry Bay (Miss M. Ball). In Scotland Mr. Jeffreys has 



