BIOLOGY 



LIBRARY 



G 



COPYRIGHT, 1891, 



BY MACMILLAN AND CO. 



First Edition, 1876. Second Edition, 1877. Third Edition, 1879. 

 Fourth Edition, 1883. Reprinted 1884, 1886. Fifth Edition, 1891. 

 Sixth Edition, revised and enlarged, 1891. Reprinted 1896. 



Norfoooti 



Berwick & Smith, Norwood, Mass., U.S.A. 



