PRINCIPLES OF ZOOLOGY 



TOUCHING 



THE STRUCTURE, DEVELOPMENT, DISTRIBUTION, 

 AND NATURAL ARRANGEMENT 



RiOES OF ANIMALS, LIVING AND EXTINCT 



WITH NUMEHOUS ILLUSTRATIONS. 

 PART T. 



COMPARATIVE PHYSIOLOGY. 



FOR THE USE OF SCHOOLS AND COLLEGES. 



LOUIS AGASSIZ and A. A. GOULD, 



KE VISED EDITION. 



BOSTON: 

 GOULD AND LINCOLN, 



59 WASHIXGTOX STREET. 



NEW YORK : SHELDON AND COMrANY. 



CINCINNATI : GEO. S. BLANCIIAKD. 



1863. 



