REPTILES OF NORTHWESTERN NEVADA AND ADJACENT 



TERRITORY. 



By C. H. Richardson, 



Of the New Jersey Agricultural Experiment Stations, New Brunswick. 



INTRODUCTION. 



The Lahontan Basin occupies the bed of the quaternary Lake 

 Lahontan and its drainage system which lies principally within north- 

 western Nevada, although ramifications of it extend into eastern 

 California and southern Oregon. This extensive drainage area in- 

 cludes a number of river systems of which the Truckee, the Hum- 

 boldt, the Walker, and the Honey Lake, are the largest. A unique 

 feature of the topography is the rather large number of " sinks' ' or 

 lakes without outlets; the Truckee system has two, Pyramid Lake 

 and Winnemucca Lake, and is also remarkable in that it finds its 

 source in the alpine Lake Tahoe. The Humboldt system looses its 

 waters in Humboldt Lake, the Carson system in North and South 

 Carson Lakes, the Walker system empties into the Walker Lake, 

 and the Susan River and Long Valley Creek systems terminate in 

 the fluctuating Honey Lake. 



The Lahontan Basin is marked by a succession of mountain ranges 

 and level plains. The predominating plant growth over the greater 

 part of this region is the " sage brush," Artemisia tridentata, which in 

 some places excludes nearly all of the other forms. Along streams 

 the cottonwood, Popuius fremontii, and willows form the most con- 

 spicuous vegetation, while on the mountains, the juniper, Juniperus 

 utahensis, grows abundantly. The flora of the desert immediately 

 south of Pyramid and Winnemucca Lakes is of a different character, 

 Sarcobatus and other shrubs largely replacing the "sage brush." 

 This difference in the flora is correlated with a greater diversity in 

 the reptilian fauna, and we find such southern forms as Oallisaurus 

 and Sceloporus magister. 



The present report is based largely upon a collection obtained by 

 Prof. J. O. Snyder, of Stanford University, and the writer, while 

 pursuing ichthyological investigations for the United States Bureau 

 of Fisheries. The expedition remained in the field from May 23 until 

 July 17, 1911. During that time collections and observations were 

 made at Truckee, Nevada County; Tahoe City, Placer County; Tallac, 

 Eldorado County; Susan ville and Doyle, Lassen County, California, 



Proceedings U. S. National Museum, Vol. 48— No. 2078. 



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