134 iv. 12. 



as a tail, stretching them out behind, and so rendering them 

 serviceable, whereas in any other position they would be simply 

 in the way.^* 



In other birds, where the legs are short, these are held close 

 against the belly during flight. In some cases this is merely 

 to keep the feet out of the way, but in birds that have talons 

 the position has a further purpose, being the one best suited for 

 rapine.^-'' Birds that have a long and a thick neck, keep it 

 stretched out during flight ; but those whose neck though long 

 is slender fly with it coiled up. For in this position it is pro- 

 tected, and less likely to get broken, should the bird fly against 

 any obstaclc^^ 



In all birds there is an ischium, but of such length that it 

 would scarcely be taken for an ischium, but rather for a second 

 thigh-bone ; for it extends as far as to the middle of the belly.^^ 

 The reason for this is that the bird is a biped, and yet is unable 

 to stand erect. For if its ischium extended but a short way 

 from the fundament, and then immediately came the leg, as is 

 the case in man and in quadrupeds, the bird would be unable 

 to stand upright at all. For while man stands erect, and while 

 quadrupeds have their heavy bodies propped up in front by the 

 fore legs, birds can neither stand erect owing to their dwarf-like ^^ 

 shape, nor have anterior legs to prop them up, these legs being 

 replaced by wings. As a remedy for this nature has given them 

 a long ischium, and brought it to the centre of the body, fixing 

 it firmly ; and under this central point she has placed the legs, 

 that the weight on either side may be equally balanced, and 

 standing or progression rendered possible. Such then is the reason 

 why a bird, though it is a biped, does not stand erect. Why its 

 legs are destitute of flesh has also already been stated ; for the 

 reasons are the same as in the case of quadrupeds.^^ 



In all birds alike, whether web-footed or not, the number of toes " 

 in each foot is four.^" For the Libyan ostrich may be disregarded 

 for the present, and its cloven hoof and other discrepancies of 

 structure as compared with the tribe of birds will be considered 

 farther on. Of these four toes three are in front, while the fourth 

 points backwards, serving, as a heel, to give steadiness. In the 

 long-legged birds this fourth toe is much shorter ^^ than the others, 

 as is the case also with the Crex.^^ In no bird is the number 

 of toes more than four. The arrangement of the toes is such 

 695a. 



