gion greatly restricts the natural vegetation. In the im- 
mediate vicinity of the site at Bat Cave Atriplex canes- 
cens (Pursh) Nutt. provides the major cover on the plain 
with species of Sporobolus and Heliotropium playing a 
secondary role. There is a distinct change in the vegeta- 
tion as one leaves the old lake floor and ascends the 
gravelly beach terraces which mark the ancient shores of 
the lake. Russian thistle, Sa/sola pestifer A. Nels., is 
common on the edge of the plain. Many species of Com- 
positae, Labiatae, Chenopodiaceae, Amaranthaceae, 
Boraginaceae and Gramineae are found on the terraces 
themselves. Where the terraces are especially rocky, 
Fallugia paradowa (I). Don) Endl. occurs as a common 
shrub with Rhus trilobata Nutt. ex Torr. & Gray and 
species of Ribes and Forsteria. During the dry season 
this vegetation has a distinctly xerophytic appearance 
accented by occasional plants of Opuntia and Mammil- 
laria. In the rainy season the vegetation becomes quite 
green, and a number of short-lived annual flowering 
plants, as well as species of Selaginella and Notholaena, 
make their appearance. 
The vegetation remains more or less the same for some 
200 to 400 feet up the slopes surrounding the basin. At 
this point a distinct change in the vegetational pattern 
occurs. Pinus edulis Engelm. and Juniperus spp. be- 
come the dominant features in the vegetation. In one 
‘anyon near Bat Cave several trees of Pinus ponderosa 
Dougl. ex P. Laws. occur, while, in some protected areas 
of this pifon-juniper belt, trees of various species of 
Quercus are found. 
Vegetation in the Past. The species identified among 
the vegetal remains found in Bat Cave would seem to 
indicate that the natural vegetation which occurs today 
is not substantially different, except in a few character- 
[215 | 
