64 



U. S. P. R. R. EXP. AND SURVEYS ZOOLOGY GENERAL REPORT. 



From St. Louis. 



Measurements. 



This species was first described from a specimen collected in Michigan by Dr. Geo. Leib. It 

 is essentially a prairie species, where it replaces the S. aquations of the east. Its extreme range 

 to the west has not yet been ascertained. 



List of specimens. 



