THE AMERICAN 



''•■7 



MONTHLY 



Microscopical Journal 



^ 



CONTAINING 



CONTRIBUTIONS TO BIOLOGY. ^ 



Volume XII 



FOR 



1891. 



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



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



WASHINGTON, D. C. 



