OR, GLIMPSES BENEATH THE WATEES. 



appears likely to produce but a slow rate of pro- 

 gress, yet some of the sand-boring Bivalves manage, 

 when alarmed, to conceal themselves with great 

 rapidity by that means. 



The Mollusca, as feeders, are divided into three 

 classes — those which take only liquid food, the 

 vegetable feeders, and the carnivorous species. 



Those which are only able to take food in a 

 liquid form, are such as have no means of seizing 

 prey, their food consisting of the countless myriads 

 of infusorial animalcules which float in the sea- water, 

 and which are carried into the orifice of the stomach 

 or mouth by the current. Of these, the Dunicata^ 

 BracMopoda^ and ConcJiifera^ are examples. 



The liquid feeders exhibit a very low form of 

 molluscous life, but other classes are furnished with 

 means of defence and aggression, equal to those of 

 terrestrial quadrupeds, and much more extraordinary 

 in their form. Some of the carnivorous Univalves^ 

 for instance, feed upon the Bivalves by drilling a 

 hole through the solid shell, and withdrawing the 

 animal piecemeal, as required. 



The Balis papillosa has been observed tearing 

 away the tentacles of different species of Sea- 

 Anemone with extraordinary voracity, and the 

 tribe must therefore very evidently be excluded 



71 



