Aves. 



243 



two groups, but if we compare the structure of modern birds 

 and reptiles, we find likenesses that are not apparent on 

 superficial examination. Feathers and scales are of the 

 same origin ; the bird has both. The feathers of the wing 

 of the penguin are scalelike. The head joins the first ver- 

 tebra in the same way in both by a single occipital condyle, 



FIG. 148. BALTIMORE ORIOLE AND NEST. 



From Grinnell's Our Feathered Friends. 



that is, the head pivots on a single rounded process, instead 

 of on two, as in our bodies. The tongue of a snake is 

 supported in the same way as in a bird, and both are more 

 or less protrusible. Both lay large eggs, and there are 

 points of development in common that cannot be con- 

 sidered here. All these facts, here scarcely hinted at, go 

 to show that birds have descended (or ascended) from 



