SAXICAVA. 149 



On the southern coasts this species may be regarded as a 

 very common and abundant shell ; in the north it is not so 

 plentiful. It is found near low-water mark upon the shores 

 of Kent and Sussex, buried in large masses of chalk (S. H.), 

 and is dredged as well as found upon the beach in de- 

 tached portions of limestone rocks at Torquay, Weymouth, 

 and other parts of Devonshire and Dorset (S. H.) : in the 

 west bay of Portland it is dredged alive in twenty fathoms 

 water (R. M'Andrew and E. F.) ; common at Scarborough 

 (Bean) ; Swansea (Jeffreys) ; around the Irish Coast 

 (Thompson). In twenty fathoms water off the Isle of 

 Man (E. F.) ; Zetland, Ullapool, Loch Oarron, and other 

 localities on the west of Scotland (Jeffreys and Barlee) ; 

 Lerwick, in seven fathoms, among LaminarieB (M'An- 

 drew) ; Frith of Forth, in seven fathoms (E. F.). In local 

 lists, this and the last species are so often mentioned under 

 the same name, that it is difficult to discriminate their 

 several localities. 



It ranges throughout the Boreal and Celtic regions of 

 the North Atlantic. Mr. M'Andrew has dredged it on 

 the north coast of Spain. It is more abundant as a pleis- 

 tocene fossil than the last species. 



Some curious little shells, of which a few pair were 

 dredged by Mr. Hanley, not far from the pier at Ryde, in 

 the Isle of Wight, and an odd valve or two were procured 

 by Mr. Jeffreys in the Island of Skye, have been figured, 

 (Plate VI. figs. 1, 2, 3,) but not designated by us, under 

 the supposition that, however different in aspect, they may 

 prove to be merely the young of the last species. Their 

 shape is ovate-oblong, but more rounded above than below ; 

 the texture is thin and fragile, but not transparent, and the 



