THE AMERICAN 



MONTHLY 



Microscopical Journal: 



CONTAINING 



CONTRIBUTIONS TO BIOLOGY 



VolaUMR XV. 



FOR 



1804. 



FOUNDED IN 1880, BY ROMYN HITCHCOCK, F. R. M. S. 



PUBLISHED, SINCE 1887, BY CHAS- W. SMILEY, 



WASHINGTON, D. C. 



