CARDIUM. 19 



the ordinary variety. The posterior ventral margin seems 

 always rounded off. 



The collective amount of these differences is very great ; 

 but all are rarely developed in the same specimen, since this 

 variety approaches to or recedes from the typical form in 

 proportion to the influx of salt-water into the brackish 

 stream in which it is engendered. Some very beautiful 

 ones, whose glossy surface is of a pale sulphur colour, are 

 obtained in the vicinity of Hastings (S. H.). The salt-water 

 marshes of Hampshire (Dr. Goodall); Arran, in Ireland 

 (Ball) ; the Murray Frith (M' Andrew), &c, may also be 

 indicated as localities. 



The edible Cockle seems met with in most parts of the 

 United Kingdoms, and is almost everywhere regarded as a 

 savoury food by the humbler classes of society. The or- 

 dinary run of examples does not exceed an inch and four- 

 fifths in length, and an inch and a half in breadth ; but in- 

 dividuals of far more ample proportions are procured on the 

 north coast of Devon (Jeffreys); the Scilly Isles (M'An- 

 drew); and in the Hebrides (Barlee). 



The animal of the common Cockle is shaped like its 

 shell, thick, subglobose, and white. The mantle is of a yel- 

 lowish hue, and differs from that of many of its allies in 

 having a considerable portion of its edges more or less fim- 

 briated, and also being furnished with a short white fila- 

 ment opposite each rib of the shell. The siphonal tubes 

 are short and slightly separated, the branchial largest, and 

 has its orifice fringed with about ten long white cirrhi, and 

 two or three intermediate small ones between each pair. A 

 reddish-brown hue encircles it, as also the anal siphon, 

 which, however, has no cirrhi on its border: the usual 

 tubular anal valve is conspicuous. The sides of the siphons 



