130 iv. 12. 



themselves,^ But, when we compare birds with other animals, we 

 find the parts differing not merely in relative size but in form. 

 Thus birds are invariably feathered, and this is a peculiarity 

 which is characteristic of them. For while other animals are 

 some hairy, some scaly, some covered with scaly plates, birds 

 alone are feathered. Insects it is true are also feathered, but 

 the feathers of a bird are split and different in kind from the 

 undivided feathers of an insect ; for the bird's feather is barbed, 

 while the insect's is not ; the bird's feather has a shaft, the 

 insect's has none.^ 



A second strange peculiarity which distinguishes birds from 

 all other animals is their beak. For as in* elephants * the nostril 

 serves in place of hands, and as in some insects ^ the tongue 

 serves in place of mouth, so in birds there is a bony^ beak which 

 serves in place of teeth and lips. Their organs of sense have 

 already been considered. 



All birds have a neck extending from the body ; and the 

 purpose of this neck is the same as in such other animals as 

 have one.' This neck in some birds is long, in others short ; its 

 length as a general rule being pretty nearly determined by that 

 of the legs. For long-legged birds have a long neck, short-legged 

 birds a short one, to which rule, however, the web-footed birds 

 form an exception. For to a bird perched up on long legs a 

 short neck would be of no use whatsoever in collecting food 

 from the ground ; and equally useless would be a long neck, 

 if the legs were short. Such birds, again, as are carnivorous 

 would find length in this part interfere greatly with their habits 

 of life. For a long neck is a weak one, and it is on their superior 

 strength that carnivorous birds depend for their subsistence. No 

 bird, therefore, that has talons ever has an elongated neck. 

 In web-footed birds, however, and in those other birds that seem 

 to belong to the same genus, inasmuch as their toes though 

 actually separate are yet flattened and expanded into lobes,^ 

 the neck is elongated, so as to be suitable for collecting food 

 from the water ; while at the same time the legs are short, so 

 as to serve in swimming. 



The beaks of birds, as their feet, vary with their modes of life. 



For in some the beak is straight, in others crooked ; straight, 



in those whose food requires that form ; crooked, in those that 



live on flesh. For a crooked beak is an advantage in fighting ; 



603 a. 



