PURPURA. 189 



with the horny protection ; the creature soon managed to turn 

 over the huge body and shell of the mussel, and resumed his 

 operations at the point where he left off when disturbed; 

 and he did this repeatedly after similar interruptions. At 

 last, quite satisfied that the breach would in time be efi'ected 

 in that way, Mr. Bates resolved to wait no longer for the 

 the process, but at once to give the voracious shell-fish an 

 opportunity of satisfying its appetite, at a smaller demand 

 of exertion from itself and of patience from its observer. 

 To this end he cut tlie muscles of the bivalve, so as to de- 

 prive it of the power of keeping its valves closed : its fate 

 was thus accelerated; it was now at the mercy of its enemy. 

 The latter no sooner perceived the valves open, than, leaving 

 his former work of boring, he seized his advantage by in- 

 serting his trunk between the valves, not in this instance 

 acting upon the general rule, that the enjoyment of an 

 acquisition is increased in proportion to the difficulty and 

 trouble of obtaining it. 



When not so unexpectedly assisted, however, the hungry 

 Purpura exhibits much patience, occupying himself for if 

 couple of days in making his way through a mussel-shell. 

 After gorging himself with a large portion of the contents, 

 he lies for weeks without attempting to procure a fresh 

 supply. 



