192 



GENERAL ORNITHOLOGY 



" scansorial " is simply one modification of the insessorial plan, and 

 has little classificatory significance — no more than that attaching to 

 the particular condition of the insessorial foot (d) which results from 

 elevation or versatility of the hind toe, as in some Cypselidm and 

 Caprimulgidce. This is an abnormality which has received no 



dalylefootofMM- Fig. 45.-Zygodactyle foot of a woodpecker, Eylotmm 



flsher, nat. size. pUeatvs, nat. size. From nature by Coues. 



special name ; it is generally associated with some little webbing 

 of the anterior toes at base, which is a departure from the true 

 insessorial plan, or with abnormal reduction of the phalanges of 

 the third and fourth toes, as explained above (Figs. 40, 41). (e) 

 The raptorial is another modification of the insessorial foot. It is 



From nature by Coues. 



Fig. 46, — Baptorial foot of a hawk, Acdpiter cooperi, nat. size. 



advantageous to a bird of prey to be able to spread the toes as 

 widely as possible, that the talons may seize the prey like a set of 

 grappling irons ; and accordingly the toes are widely divergent from 

 each other, the outer one in the owls and a few hawks being quite 

 versatile. In a foot of raptorial character, the toes are cleft pro- 



