
188 THE NATURALIST IN CALIFORNIA. 
In such a region the higher animals cannot be expected to 
abound, and those found are chiefly stragglers from more 
favored tracts, but still there are some of much interest. De- 
scending the eastern slope we find Harris’s Squirrel ( Sper- 
mophilus Harrisii) scarce at'this cold season, but common 
on our return in June. This little animal has much the ap- 
pearance and habits of Tamias, but is nearly white. I saw 
also tracks of the Sage Fowl (Centrocercus urophasianus) 
corresponding in color with the granite rocks among which 
it lives, and have seen a specimen killed near here. : 
"The only peculiar bird known is Leconte’s Mock-thrush 
(Harporhynchus Leconte’), which is also of a pale grayish 
brown, like a faded specimen of the coast species (H. redi- 
vivus), but is admirably colored for concealment among the 
thorny bushes growing on the sand-hills it inhabits. Both 
of these animals having dark colored representatives in less 
barren regions, offer excellent instances of the influence of 
“natural selection,” but have some peculiarities not to be 
explained by the influence of the climate and country they 
inhabit. 
The road for nearly one hundred miles eastward follows 
the Mojave River, which, being permanent for half that dis- 
tance, and supplying moisture to a narrow tract of bottom- 
land, forms a sort of oasis in the desert, cultivable, and with 
its upper parts lined with trees and shrubs. Some of the 
vommon Californian birds were rather frequent here, but I 
found none of interest at that season. On returning in June 
I found here the Purple-throat Humming Bird, the Little 
Vireo, and various other summer species. Fresh water 
shells of the genera Lymnea, Physa and Planorbis occurred, 
also two species of Succinea, in the more elevated cool parts 
"e .. of the valley. 
It is in the class of reptiles, and especially lizards, that 
the fauna of the desert excels. Although none were visiblo 
. in December, and I had not time to collect many on my re- 
turn in June, I have ascertained that seventeen species have 



