974 The American Naturalist. [November, 
sage-brush, I reached the house of Mr. George Duncan, on the 
shores of Silver Lake. The next day after I arrived, the guide 
and one soldier came in with a note from the Corporal stating that 
the wagon had broken down, and they could get no farther ! So I 
hired a man to go and bring on my stuff, and then the soldiers 
hired him to take their part of the load back to Fort Klamathe 
Silver Lake measures about twelve miles long by eight miles 
wide. It is supplied with fresh w^ater from Silver Creek which 
enters it from the north-west and has a swampy delta. The 
Salmo purpiiratus are numerous in the creek, but they do not 
enter the lake, owing to the alkaline character of its waters. A 
smaller fresh stream enters at about the middle of the western 
shore. The lake is bounded on the west and east by precipitous 
basaltic bluffs (Plate XL.) On the south the bluffs present their 
dip edges to the lake, since the general strike is north and south. 
As I have observed in the lakes further south, i. e.. Pyramid 
Lake, Nevada, and Warner's, Abert and Summer Lakes, Oregon, 
the basaltic beds dip away to the east from the bluffs which 
bound the east sides of the lakes, showing that the latter occupy 
fissures or fractures in the beds, which have a north and south 
direction. On the north side Silver Lake is bounded by a range 
of low hills, terminating in a bold flat-topped butte to the east, 
which is composed of volcanic mud more or less irregularly 
stratified (PI. XLI.) A low shore and plain separate this range 
from the eastern bluffs, and at this point, overflow from the lake 
reaches a low tract to the eastward, which, when it contains 
water, is known as Thome's Lake. It was dry at the time of my 
visit, (1879). On climbing the bluff which bounds the lake on 
the west, the observer stands on the edge of a plain which ex- 
tends to the foot of the ancient volcano which I passed on the 
way to the lake. It is here seen to form but a single mountain 
with its foothills, forming a line north and south. It occupies the 
position of the so-called " Winter Range " of the U. S. War De- 
partment maps ; but it is rather entitled to be called Winter Moun- 
tain than a " range." Its summit is bold, but had no snow on 
it at the time of my visit (Fig i). Its slopes are thickly 
clothed with forests of pine {Pinus ponderosd). 
