Limpets. 105 



flat and concave form of the two valves of this 

 shell, and also the depth of the indentations or 

 ridges. 



LIMPETS. 



Among the rocks of the British coast there are 

 no shells more frequently met with than those of 

 the Common Limpet (Patella vulgata) ; they lie 

 scattered about like so many little empty cups, each 

 having, on the death of the molluks, fallen from the 

 rocky cavity in which it was embedded, and which 

 was just large enough to contain it. Here the 

 animal attaches itself so firmly by its fibrous foot, 

 which is hollow in the centre, and acts like a sucker, 

 that it is almost impossible to loosen its hold other- 

 wise than by inserting something thin, like the 

 blade of a knife, between it and the stone. By this 

 power of adhesion, the Limpet is protected from the 

 violence of the waves, and also from its numerous 

 enemies, aquatic birds and animals, which have a 

 relish for its flesh. Still vast numbers are used as 

 food, both by man and the inferior creatures, so 

 that the means of defence furnished to the Limpets 



