100 



This species is taken abundantly at Exmouth, of all sizes, 

 in the coralline zone. 



C. EDULE, Linnaeus. 

 C. edule, Brit. Moll. ii. p. 15, pi. 32. f. 1-4; (animal) pi. N. f. 5. 



Animal suborbicular ; the body is large, subglobose, and of 

 an opake white; mantle pale yellow, edge fringed. The 

 siphonal apparatus forms two short conical tubes, separate 

 from their bases, and divergent; the branchial has ten long 

 white cirrhi, with two or three intermediate shorter ones 

 springing from the orifice, which is encircled by a dark or 

 red-brown line; the anal tube has a similar line, but no 

 cirrhi; it is provided with a retractile tubular valve ; both tubes 

 have on their surfaces the usual characteristic curly white 

 filaments, and they vary from whitish to pale yellow or red- 

 dish-brown. The foot is considerably smaller than in any of 

 the other Cardia, and has very little of the long cylindrical 

 aspect of that organ in its congeners, being rather flat and 

 lanceolate ; its colour varies from opake white to pale brown 

 or yellow. There are a pair of moderate-sized, pale brown, 

 suboval branchiae on each side, finely pectinated, the upper 

 one being much the smallest ; the palpi are red-brown, longish, 

 pointed, flat, and subtriangular, smooth on the outside and 

 pectinated within. 



There are many varieties of this common species which 

 result from habitat; they are sometimes excessively thin, 

 arising in certain estuaries from a more than usual affusion of 

 fresh with the salt water, and under those conditions have 

 been named by some naturalists C. rusticum. It is proper to 

 observe, that the true Linnsean C. rusticum is a very different 

 species, which has long been known to collectors, though 

 misnamed C. tuberculatum, the strongest and most ponderous 

 of all the Cardia. The young of one of the varieties, from its 

 umbonal transverse bands, has been mistaken for our (7. fas- 

 datum, the C. elongatum of some authors, but the oblique out- 

 line of the latter species will always distinguish it from any of 

 the young fasciated varieties of C. edule. 



