THE WONDEES OF THE SHOEE. 69 



" C. tuberculatum," says Mr. Gosse (wlio described 

 it from specimens wliicli I sent him in 1854), "is 

 far tbe finest species. The valves are more globose 

 and of a warmer colour ; those that I have seen are 

 even more spinous." Such may have been the case 

 in those I sent : but it has occurred to me now 

 and then to dredge specimens of C. aculeatum, 

 which had escaped that rolling on the sand fatal 

 in old age to its delicate spines, and which equalled 

 in colour, size, and perfectness, the noble one figured 

 in poor dear old Dr. Turton's "British Bivalves." 

 Besides, aculeatum is a far thinner and more 

 delicate shell. And a third species, C. echinatum, 

 with curves more graceful and continuous, is to be 

 found now and then with the two former, in which 

 each point, instead of degenerating into a knot, as 

 in tuberculatum, or developing from delicate, flat, 

 briar-prickles, into long, straight thorns, as in acu- 

 leatum, is close-set to its fellow, and curved at the 

 point transversely to the shell, the whole being thus 

 horrid with hundreds of strong tenterhooks, making 

 his castle impregnable to the raveners of the deep. 



