A LABORA 



NUAL OF 



INVERTEBRATE 

 ZOOLOGY 



BY 



OILMAN A. DREW, PH.D. 



ASSISTANT DIRECTOR OF THE MARINE BIOLOGICAL LABORATORY, 

 WOODS HOLE, MASSACHUSETTS 



WITH THE AID OF 



FORMER AND PRESENT MEMBERS OF THE 



ZOOLOGICAL STAFF OF INSTRUCTORS AT 



THE MARINE BIOLOGICAL LABORATORY 



WOODS HOLE, MASS. 



THIRD EDITION, REVISED 



PHILADELPHIA AND LONDON 



W. B. SAUNDERS COMPANY 



1924 



