2 University of Michigan 



Pinyon Ranges which surround it. The valley is drained by 

 the Humboldt River, which flows across the south end, and its 

 tributaries, the principal ones being knowai as Maggie, Annie, 

 Susan and James creeks. The Humboldt River and Maggie 

 Creek are the only i)ermanent and continuous streams in the 

 valley, the others becoming either entirely dry or discontinuous 

 •in the summer. These creeks are fed from numerous canyons 

 in the surrounding mountains, which for the hiost part become 

 entirely dry in the summer. Occasionally, springs, more or 

 less continuous, are found. 



The region is an arid one. The sage brush covers the 

 whole area to the summit of the ranges. There is no forest 

 and, except for the willows and shrubs along the permanent 

 water courses and small groves of poplar, buffalo berry and 

 other small trees and shrubs in the mountain canyons, the 

 region is treeless. 



As might be expected, the molluscan fauna is very meagre, 

 as indeed it is throughout the Great Basin. 



In 1884 R. E. Call published an elaborate report "On the 

 Quarternary and Recent Mollusca of the Great Basin", (Bull. 

 U. S. Geol. Survey, No. it. pp. 359-410), which embodied all 

 of the information in regard to the fauna available, at that 

 date. Call's luaterial came mostly from tiie western part of 

 the state, in the Pyramid Lake region, but he also lists a few 

 (four marked with an asterisk in the Call column given below) 

 species from the Humboldt River at Elko, which is a little 

 east of the area covered by the University Expedition. His 

 list of the recent species known to him from the Lahontan 

 Area is, therefore, of interest as a 1)asis of comparison of the 

 faunas of the eastern and western portions of the state. This 

 is shown by the following table. 



