Beaks and Bills 22 
reaching about, or for progression being understood. But 
no one would think of alluding to a bird’s lips or nose; both 
are included in the terms beak, or bill, and nostrils. 
The finding and securing of food being the most im- 
portant problem which birds have to solve for themselves, 
it is for these purposes, and especially the last mentioned, 
that we find bills most adapted. This is so universally 
Fic. 163.—Bill of American Raven. 
the case that we may often judge accurately of the kind 
of food of a certain bird from a glance at its beak. 
As is the case with so many other avian structures, 
the horny, toothless beak or bill is duplicated elsewhere 
in Nature only in a group of reptiles, the turtles and tor- 
toises, whose mandibles furnish a splendid example of 
parallel evolution. 
In certain of those long-extinct Dinosaurs, such as 
