108 The Bird 
spinal chord passes into the brain, and below it is a 
small knob, which in the living bird fitted into the first 
vertebra of the neck. It is a very tiny projection of 
bone, but fraught with significance: for if we look at 
the skulls of a frog, a mouse, a cat, a horse or aman, we 
will see that the head hinges upon two bony projections, 
but in all birds and reptiles there is but one,—a very 
Fig. 84.—Rear views of bird (Hornbill) and mammal (Yaguarondi) skulls. Notice 
single facet (occipital condyle) in the bird and two in the mammal, connecting 
skull with the neck-bones. 
plain hint of the relationship of these two Classes, so dif- 
ferent in external appearance. The head thus pivoting 
upon a single point, the bird can turn its head much 
farther around than if there were two points of attach- 
ment. Before we leave this great opening, as the scien- 
tists call it when they speak of it as the foramen magnum, 
it may be worth while to mention the remarkably con- 
stant position of the bones around it. Whether these 
are all separate, or solidly fused into one, we may always 
