A BIRD’S FOREFATHERS. 3 
ancestral outlook of the birds, therefore, lies in the 
aspirations of the lizards. 
But real bird hfe begins higher up the line still, 
where flight became very special—not by skin, but 
by scales with some changes wroughtin them. So far 
as our knowledge goes, no creature except a bird ever 
flew by feathers. It may be possible that there were 
some soft modifications of the scales among the active 
terrestrial reptiles, but, so far as we now know, nothing 
but a bird has ever worn feathers—except a woman 
and a savage. Better to say that nothing but a bird 
grows feathers. 
Birds show that their forefathers were among the 
reptiles by the following characters common to both, 
and by many others too technical for our discus- 
sion : 
The large egg noted, found nowhere else except 
in that three-way connecting link between _ birds, 
reptiles, and mammals—the duckbill group; by the 
lack of complete diaphragm below the heart and 
lungs; by having only a single ball-and-socket joint 
where the head turns on the neck, whereas the mam- 
mals and amphibians have two: by many peculiarities 
of structure about the head, especially by having the 
lower jaw connected to the skull by an intervening 
(quadrate) bone not found in the mammals. So also 
there are peculiar arrangements of the circulatory sys- 
tem and of the bones of the feet, etc., that are found 
only in these two groups. Finally, as distinctive of 
the groups, they neither pass through a tadpole or in- 
complete state after birth, as the amphibians, or have 
