THE AMERICAN 



i 



MONTHLY 



Microscopical Journal 



CONTAINING 



CONTRIBUTIONS TO BIOLOGY. 



Volume XII. 



FOE 



1891. 



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



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



WASHINGTON, D. C. 



