88 The Bird 
no matter how much change has occurred in their 
shape and size. Take, for instance, the shoulder-blades. 
When a tiger crouches they are very conspicuous, and 
whether we take a frog, a turtle, a lizard, an armadillo, 
a mouse, or a horse, we may always be sure of finding a 
scapula in the region where we have observed it in the 
bird. This is an important fact, and one which makes 
the identification of many bones an easy matter. 
Thigh-girdle 
The shoulder-girdle which we have just examined 
was not joined to the back-bone, but only saddled on 
the ribs, the scapula extending backward, just clearing 
them. What kept it in place in the chicken’s skeleton 
was the fact that it was strongly attached to the sternum, 
and this in turn joined to the back-bone by means of 
the ribs. But the pelvic arch or thigh-girdle is very 
different. If the entire framework of the bird is to be 
supported on two legs, the point of attachment of these 
limbs must be solidly fixed to the back-bone of the body. 
Although there are as many bones supporting the leg 
or thigh as there are bracing the shoulder, we would 
never know this from examining our chicken. As in 
other places in a bird’s skeleton, the bones—six in this 
case—have fused together in one solid piece, and only 
in very young birds are they separate.* 
The names of the bones composing the pelvic girdle, 
or arch, are the ilium, ischium, and pubis. The easiest 
* They were separate also in Archeopleryr. 
