PARTS OF ANIMALS, IV. xiii. 



others have it underneath {e.g. the dolphin '^ and the 

 selachians) and that is why they turn on to their backs 

 to get their food. It looks as if Nature made them 

 do this partly to preserve other animals from them, 

 for they all prey on living things, and while they are 

 losing time turning on to their backs the other things 

 get away safely ; but she did it also to prevent them 

 from giving way too much to their gluttonous craving 

 for food, since if they could get it more easily they 

 would presently be destroyed through repletion. 

 Another reason is that their snout is round and small 

 and therefore cannot have much of an opening in it. 



There are differences too among those that have 

 their mouth above. With some it is a great wide 

 opening (these are the flesh-eaters, as e.g. those mth 

 sharp interfitting teeth, whose strength is in their 

 mouth) ; with others (the non-flesh-eaters) it is on 

 a tapering snout. 



As for the skin : some have a scaly skin (these Skin, 

 scales are shiny and thin and therefore easily come 

 loose from the body) ; others have a rough skin, e.g. 

 the Rhine and the Batos and such. Those with 

 smooth skins are the fewest. Selachia have skins 

 which are scaleless but rough, owing to their bones 

 being cartilaginous ; instead of using the earthy 

 matter on the bones Nature has used it for the skin. 



No fish has testicles ^ either without or within. Nor Testicles. 



the creature, some editors consider this reference to be an 

 interpolation. 



^ By this Aristotle does not mean that fish have no organ 

 for the secretion of sperm, but that they have no organ similar 

 in shape and consistency to those of mammaha, etc. He calls 

 the corresponding organs in fish not testes, but tubes, or roe. 

 Aristotle's statement does not, of course, include the Selachia, 

 which have compact, oval testes. 



425 



