The Framework of the Bird gl 
the adult bird the shifting backward of this bone until it 
i 
Dn 
parallel with the ischium is wholly an avian feature. 
Fic. 66.—Bullfrog. The bend in the back shows the great development of the 
ilium for bipedal locomotion in the sense of leaping ability. 
Wings 
We will now consider the framework of the fore limb, 
or wing, of a bird, and a glance at the illustration show- 
ing the arm of a man and the wing of a bird will at once 
make plain the relation between the two. Here we again 
find a great help in the fact that many of the bones keep 
to their respective places in frogs, lizards, birds, and man. 
We know but little of the direct change from a fin to 
a hand or foot, although there are some fishes living at 
the present day with large finger-like bones in their pec- 
