PERIWINKLES WHELKS. 25 



the vegetable surface was then examined, and found 

 to be nibbled in a circular manner, resembling the 

 anterior margin of the shells." * 



By this mole-like burrowing in the rock, the Limpet 

 is enabled to resist the violence of the waves, and also 

 to prevent birds of prey, as gulls and others, from 

 destroying him. This they are apt to do by forcing 

 their bills under his shell, when he, not anticipating 

 danger, looses his muscular hold, and allows his tes- 

 taceous canopy to be raised above the surface of the 

 stone. 



If suddenly disturbed, the Limpet has the power of 

 ejecting a cement, by means of which it glues itself 

 to the rock so firmly, that, according to Keaumur, a 

 pressure of twenty-eight to thirty Ibs. is required to 

 overcome this adhesive force. Whenever the young 

 zoologist wishes to capture a specimen, he should 

 endeavour to fix upon one asleep. Let him then 

 softly insinuate the blade of his knife under its shell, 

 and tilt the animal suddenly over. Should the sur- 

 prise have been ineffectual, it is useless to make for 

 the present another attack upon the same animal, for 

 he would permit his shell to be chipped into a thou- 

 sand bits before he would abandon his hold. 



Wedged among rocks and loose stones, we fre- 

 quently meet with large shells of the Buccinum 

 undatum^ a species of Whelk. These are made 

 pretty often to serve as dwelling-places to adult and 



* "Mag. Nat. Hist.," vol. iv. 



t Buccinum, so called from its resemblance to a conch shell. 



