A 



BIOLOGY 

 LIBRARY 



G 



FEINTED BY C. J. CLAY, M.A. & SONS, 

 AT THE UNIVERSITY PRESS. 

 <J 



First Edition 1876. Second Edition 1877. 

 Third Edition 1879. Fourth Edition 1883. 

 Reprinted 1884, 1886. Fifth Edition 1888. 



