10 The Bird 
the Chinese, or that mankind is descended from the chim- 
panzee or gorilla. 
For the purpose of making more clear and interesting 
the ways in which birds have become especially adapted 
to their surroundings and needs, we may consider Arche- 
opteryx as resembling closely the typical original bird- 
type from which all others have at least indirectly evolved; 
and thus having obtained a definitely fixed starting-point, 
we may consider how some of the more representative 
birds of the present day came to acquire their widely 
differing structure and characteristics.* 
The tree of evolution of reptiles may be compared to 
a growth where several great trunks spring from the 
ground close together, towering up separately but equally 
high; the topmost twigs of which are represented by the 
living species of serpents, turtles, lizards, and crocodiles 
respectively. A very different arboreal structure is pre- 
sented in the genealogical tree of the Class of birds. Here, 
from a short trunk, we have many radiating branches, 
widely spreading and with thickly massed twigs, confu- 
sedly intermingled; so shght are the divergences between 
adjoining groups and so equally do almost all share be- 
tween them various reptilian characteristics. 
It is not necessary to concern ourselves now with the 
processes of evolution, especially as scientists are still in 
doubt as to the exact methods. Let us read our Darwin, 
and hope for another, philosophically as great, to com- 
* There are one or two reasons for regarding -Archwopterys as merely 
the tip of a parallel branch, but one sprouting close to the base of the ayian 
tree. 
