ARISTOTLE. 61 



and of these some have two, others four wings. 

 Those which are of large size, or bear a sting be- 

 hind, have four ; but the smaller and stingless, two 

 only. Those which have sheaths to their wings, 

 have no sting ; but those which have two wings 

 are furnished with a sting in their fore part, as the 

 gnat. 



Animals are distinguished from each other, so as 

 to form kinds or families. These, according to our 

 author, are quadrupeds, birds, fishes, cetacea, all 

 which he says have (red) blood. There is another 

 kind, covered with a shell, such as the oyster ; and 

 another, protected by a softer shell, such as the crab. 

 Another kind is that of the mollusca, such as the 

 cuttle-fish ; and lastly, the family of insects. All 

 these are destitute of (red) blood. 



Here, then, we have a general classification of 

 animals, which it is important to notice, as we may 

 have occasion afterwards to compare it with ar- 

 rangements proposed by other naturalists. It may 

 be reduced to the following form : — 



Red-hlooded Animals. 



Quadrupeds, Serpents, Birds, Fishes, Cetacea. 



White-blooded Animals. 



Testacea, Crustacea, Mollusca, Insects. 



It must, however, be understood, that Aristotle 

 proposes no formal distribution of animals, and that 

 his ideas respecting families, groups, or genera, such 

 as those of our present naturalists, are extremely 

 vague. 



His quadrupeds include the mammalia and the 

 quadrupedal reptiles. He divides them into those 

 which are viviparous, and those which are ovipa- 

 rous ; the former covered with hair, the latter with 

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