VENUS VENUS. 169 



of the beaks towards the areola, at once deter- 

 mine a shell to be a Venus, but these marks are 

 sometimes wanting ; in a few species there are 

 four cardinal teeth in each valve, and this is the 

 distinguishing mark of the genus separated from 

 this, under the name Cytherea. Those Ve- 

 neres which have only two teeth in each valve, 

 belong to the modern genus Crassina. 



The Venus is diffused over every part of the 

 world, and in many countries affords to animals 

 and birds a nutritious food. It is curious to 

 observe the contrivances by which the sea-fowl 

 endeavour to procure the mollusks of this and 

 other genera ; they have been seen to take 

 advantage of a moment, when the shell is 

 open, to drop a pebble between its valves, 

 which being thus prevented from closing, the in- 

 mate is left exposed to their attacks. Sometimes 

 when they find the shell so hard as to resist all 

 their efforts to break it with their beaks, they 

 ascend to some lofty eminence, and letting it 

 drop upon rough or craggy rocks, it is crushed in 

 the fall, and the animal thus becomes their prey. 

 The mollusk of the Venus has two siphons 

 formed by the mantle, and a lamellar foot. 



VENUS Mercenaria. 



MONEY VENUS. 



Specific Character. Shell ponderous, ob- 



