Comparative 

 EmDryolo^y 



or tne 



Vertebrates 



by 

 Olin E. Nelsen, M.A., Ph.D. 



Department of Zoology 

 University of Pennsylvania 



With 2057 Drawings and Photographs 

 Grouped as 380 Illustrations 



New York Toronto London 



McGRAW-HILL BOOK COMPANY, INC. 



W43' 



