I NT110DUCT0RY CHAPT EE. 



7 



apparatus is adapted in every case. Amongst those which 

 are carnivorous, some are furnished with appendages, by 

 which they can capture their prey, as the Cephalopoda ; 

 others, that are fixed, by producing a slight current, 

 obtain a constant stream of water supplied to their mouths, 

 bringing with it minute animals, which they retain ; as 

 the oyster. The mouth of many is in the form of a pro- 

 boscis (a) (which is unusually long in Mitra episcopalis), 



Mitra ciriscopalis. 



and is furnished with little hooks (b), with which they 

 can penetrate the shells of those they feed on, and extract 

 the contents by drilling a little round hole (often seen on 

 shells, particularly bivalves), the inhabitants of which are 

 thus entirely destroyed by their enemy. Those which 

 are herbivorous, or have no proboscis, cut their food by 

 the aid of a tongue, which is rough with recurved spines 

 and teeth, and is really a very formidable apparatus. 

 This, as seen by the aid of a good microscope, is a very 

 curious object, being formed like a ribbon, with a row of 

 jagged teeth in the centre, and frequently three rows of 

 hooks on each side. 



Molluscous animals are oviparous, producing their young 

 from eggs in the same way as birds, although many of 

 them do not, Avhen they are deposited, abandon them at 

 once, but place them for a time between the two mem- 

 branes of the branchial laminae, where they undergo a 

 species of incubation. Mollusca are extremely prolific; 

 it is slated that mussels produce 300,000 young in one 



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