158 BIVALVES. 



always narrower than the areola. The hinge has 

 either one or two central teeth in each valve, 

 one of them often bifid ; * the lateral teeth are 

 remote, and sometimes wanting in one valve : the 

 beaks are short, and usually lean towards the 

 ligament, which is external. 



OBSERVATIONS ON THE SHELL AND ITS 

 INHABITANT. 



This and the following genus are so very 

 similar, that it is often difficult to discriminate 

 between them. If however a shell have its an- 

 terior slope compressed, or any indication of its 

 margin being curved inwards, it may be known 

 immediately as a Tellina. The Tellinae are very 

 beautiful, and are particularly remarkable for the 

 coloured radiations with which they are adorned. 

 They have generally a fine polish, and are some- 

 times delicately marked with minute strise. They 

 are found buried in the sand or fine gravel of the 

 sea shore ; where they are commonly the prey 

 of Buccina, and other carnivorous mollusks, who 

 pierce the shell, and devour the inhabitant. The 

 mantle of the animal is formed in the front into 

 two siphons ; the foot which it thrusts out of its 

 shell when desiring to change its position, is 

 generally flat, but sometimes it is straight and 

 lengthened into a kind of leg. 



* Bifid, cleft in two, from the Latin bis twice, and fid t, I 

 have cleft. 



