PROGRESSION OF ANIMALS, xviii.-xix. 



resemble fishes. For birds have their wings in the 

 upper part of their bodies, fishes have two fins in 

 their fore-part ; birds have feet on their under-part, 

 most fishes have fins ** in their under-part and near 

 their front fins ; also, birds have a tail, fishes a tail-fin. 



XIX. A question may be raised as to what is the 

 movement of testaceans,^ and where their movement 

 begins if they have no right and left ; for they 

 obviously do move. Must all this class be regarded 

 as maimed and as moving in the same way as an 

 animal with feet if one were to cut off its legs, or as 

 analogous to the seal and bat, which are quadrupeds 

 but malformed ? '^ Now the testaceans move, but 

 move in a way contrary to nature. They are not 

 really mobile ; but if you regard them as sedentary 

 and attached by growth, you find that they are 

 capable of movement ; if you regard them as pro- 

 gressing, you find that they are sedentary. 



Crabs show only a feeble differentiation of right 

 and left, but they do show it. It can be seen in the 

 claw ; for the right claw is bigger and stronger, as 

 though the left and right wished to be differentiated. 



So much for our discussion of the parts of animals 

 and particularly those which have to do with progres- 

 sion and all change from place to place. Now that 

 these points have been settled, our next task is to 

 consider soul.** 



has led some critics {e.g. Brandis) to reject the whole of this 

 paragraph as a later addition. Such a paragraph, however, 

 is a characteristic conclusion in Aristotle, and should not be 

 rejected as a whole. It is quite possible that the words 

 77-ept 4'^xi^ ^re corrupt, and indeed the word i/rfx^^ h^s been 

 supplied by a later hand in Z, whereas the first hand had 

 left a blank and had written loj-qa {sic) in tlie margin, which 

 would be a reference to the latter part of the group of treatises 

 known as the Parva Naturalia. 



.S2 541 



