[ARTICLE 6. EXTRACTED FROM THE BULLETIN OF THE U. S. fetSH COMMISSION 

 FOR 1891. Pages 207 to 258. Plates XXXVII to XLII.] 



A PRELIMINARY REPORT 



ON THE 



Aquatic Invertebrate Fauna of the Yellowstone 



National Park, Wyoming, and of the 



Flathead Region of Montana. 



BY 



S. A. FORBES, 



PROFESSOR OF ZOOLOGY, UNIVERSITY OF ILLINOIS. 



[Date of publication, April 29, 1893.] 



WASHINGTON : 



GOVERNMENT PRINTING OFFICE. 

 1893. 



S AVICES 



