A MANUAL 



OF THE COMMON 



INVERTEBRATE ANIMALS 



EXCLUSIVE OF INSECTS 



By 



HENRY SHERRING PRATT, Ph.D. 



Professor of Biology in Ha^erford College and Instructor in Comparati<ve 



Anatomy in the Marine Biological Laboratory at Cold 



Spring Harbor, Long Island 



WITH OVER ONE THOUSAND 

 ILLUSTRATIONS 



SECOND EDITION 





7v 



CHICAGO 



A. C. McCLURG & CO. 



1923 



