150 GENERAL ORNITHOLOGY. 
one either; seen in those perching birds i je use their feet for progression, but 
simply for sitting motionless. (¢) The zygoda ryle or yoke-toed modification has been suffi- 
ciently noted (fig. 45). It was formerly made much of, as a scansorial or climbing type of foot, 
and an absurd ‘ 
of birds has been called 
Scansores. But many 
of the zygodactyle birds 
do not climb, as the 
order ”’ 
euckoos; while the most 
nimble and adroit of 
climbers, such as the 
nuthatches and creepers, 
retain a typically pas- Fic, 45.—Zygodactyle foot of a woodpecker, Hylotomus 
serine foot. The ‘sean- Pi/eotus, nat. size. 
sorial ” is simply one modification of the imsessorial plan, and has little clas- 
cer ee sificatory significance, —no more than that attaching to the particular con- 
fisher, nat. size. dition of the insessorial foot (@) which results from elevation or versatility of 
the hind toe, as in some Cypselid@ and Caprimulgide. 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 abnorinal 
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 
Fa. 46. — Raptorial foot of a hawk, Accipiter cooperi, nat. size. grappling irons; and accord- 
ingly 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 profoundly, or, if united 
at base, it is by movable 
webbing; the claws are im- 
mensely developed, and the 
under-surfaces of the toes are 
scabrous 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 cwrsorial or grallato- 
rial type. The gist of this 
plan lies in the decrease or 
Fic. 47. — Raptorial foot of an owl, Aluco flammeus, 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, 
