130 



GENERAL ORNITHOLOGY. 



Fig. 45. — Zygodactyle foot of 

 pileatus, nat. size. 



JJijIolomus 



Fig. 44. — Syn- 

 dactyle foot of king- 

 fisher, nat. size. 



the hind toe, as 



one either ; seen in those perching hirds which scarcely use their feet for progi-ession, but 

 simply for sitting motionless, (c) The zygodactyle or yoke-toed modification has been suffi- 

 ciently noted (fig. 45). It was formerly made much of, as a scansorial or climljing type of foot, 

 and an absurd "order" 

 of birds has been called 

 Scansores. But many 

 of the zygodactyle bird.s 

 do not climb, as the 

 cuckoos ; while the most 

 nimble and adroit of 

 climbers, such as the 

 nuthatches and creepers, 

 retain a typically pas- 

 serine foot. The " scan- 

 sorial " is simply one modification of the insessorial plan, and has little clas- 

 sificatory significance, — no more than that attaching to the particular con- 

 dition of the insessorial foot (d) which results from elevation or versatility of 

 some Oypselidce and Caprimulgidce. This is an abnormality which has 

 received no special name ; it is generally associated with some little webbing of the anterior 



toes at base, which is a de- 

 parture from the true inses- 

 sorial 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 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 

 Fig. 46. — Raptorial foot of a hawk, Accipiter cooperi, nat. size. grappling irons ; and accord- 



ingly the toes are widely divergent fi-om 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 profoundly, or, if united 



^_,;^c;^ at base, it is by movable 

 ' ^ webbing; the claws are im- 



mensely developed, and the 

 under- surfaces of the toes are 

 scabi'ous or bulbous for greater 

 security of the object grasped. 

 Any hawk or owl or old-world 

 vulture exhibits the raptorial 

 insessorial foot (figs. 46, 47). 

 2. The mrsorial or grallato- 

 rial type. The gist of this 

 plan lies in the decrease or 

 Fig. 47. — Raptorial foot of an owl, .-IZmco ^ammews, nat. size. entire loss of the grasping 



function, and in the elevation, reduction in length, or loss of the hind toe; the foot is a good 

 foot, but nothing of a hand. The columbine birds, which are partly terrestrial, partly arboreal, 



