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CHAPTEE IV. 

 Sub-Kingdom MOLLUSCA. 



" There are more things in heaven and earth, Horatio, 

 Thau ai'e dreamt of in om- philosophy." 



Cephalopods_, a group of active, voracious animals, stand 

 first in the molluscous series. Their name is derived from 

 two Greek words, signifpng a head and foot, and their 

 physiological condition is not much inferior to that of fishes. 

 They are all marine, inhabiting deep water, and only a 

 limited number produce a shell of any particular substance. 

 The head and body resemble an oblong bag, of which the 

 upper portion is crowned with numerous arms, or tentacles, 

 covered with suckers ; and, as their name implies, they walk 

 with the head downwards. 



Gastropods comprise a numerous class, whose habits are 

 less active than those of the preceding, and in whom the 



