288 CARDIID^. 



inclined to refer to it also some fossil shells which the Rev. 

 H. B. Tristram brought home from the Great Sahara 

 and sent to Sir Charles Lyell. 



The mode bv which the cockle burrows in sand with 



it 



its dibble-shaped foot (called by Paley " its stiff tongue") 

 has been already described : but Mr. Dennis informs 

 me of another habit, with which I was not before ac- 

 quainted. He says, " I found a large specimen of the 

 common cockle moored by a byssus to a stake in the 

 mill-creek. It might be eighteen inches up the stake. 

 The run of the water is very strong at the spot, and 

 the bottom shingle." This confirms an observation of 

 the same kind made by Costa with regard to a variety 

 of C. exiguum, and which I have before noticed. Phi- 

 lippi expressed his disbelief of Costa's statement; but 

 there is nothing wonderful in the cockle or any other 

 animal acquiring a new habit under altered circum- 

 stances, especially if such habit is not inconsistent with 

 its general organization. It may arise from the deve- 

 lopment of a mysterious faculty, closely allied to one 

 which in our pride we call reason, and consider to be our 

 own exclusive property. But boast not, O Man, of your 

 superiority to other animals in this respect ! Your and 

 their Creator may, if he think fit, grant the same 

 mental privileges as you enjoy to the brute, and even 

 to the mollusk. See what Coleridge has to say on the 

 subject : 



" And what if all of animated nature 

 Be but organic harps diversely framed, 

 That tremble into thought, as o'er them sweeps, 

 Plastic and vast, one intellectual breeze, 

 At once the soul of each, and God of all." 



The shape of the cockle is extremely variable. In 

 sheltered or still water, where the ground is muddy or 



