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BIOLOGY 

 LIBRARY 



G 



First Printed 1875. Printed and Stereotyped 1876. 

 Reprinted March and Jitly 1877, February and December 1879, 

 1882, 1883, 1885, March, September, December, 1886, 1887. 

 Revised and extended edition, 1888. 

 Rerinted 



