S6 



CLASS COXCHIFERA. 



in again sinking to the bottom. This movement is, no 

 doubt, produced by the action of the foot, which forms 

 itself into a sharp point in its descent, and when it 

 remounts is 'enlar<!:ed as much as possible, to form a 

 resting-point, for the purpose of raising the shell to the 

 surface. It is not supposed that the animal ever entirely 

 leaves its hole of its own accord, although it may possess 

 the power; but it is certain, according to the observations 

 of Reaumur, that if forcibly removed it can re-enter it. 

 The hole it forms for its retreat is always perpendicular. 



^A- 





TdUna. 



Solen rar/ina. 



Pandora rostrata. 



One of these creatures, being taken out of its retreat, 

 was laid on the sand ; it first extended its foot in the 

 form of a wedge, or rather cone, and, applying it to the 

 surface of the sand, slightly raised the farthest end of 

 its shell: at the next efibrt the projecting part of the 

 foot was buried in the sand, and the shell became more 

 elevated ; after two or three more attempts the hole had 

 attained a perpendicular direction, and the shell was 

 partly buried in it; the shell then began to descend, 

 and that with considerable quickness. 



The Solens are used sometimes, but rarely, for food ; 

 but in places where they abound, they are sought after 



