56 SNAKE RIVEU PLAINS OF IDAHO. [bull. 199. 
canyon widens into a valley, frequently (3 or 8 miles broad, with a 
precipitous escarpment on the northern side and a less steep and less 
regular line of bluff's forming its southern border. 
FOSSILS. 
At Shell Mountain and near Glenns Ferry a large number of fresh- 
water shells were collected, which, as determined by W. H. Dall, 
belong to the following species: Lithasia antiqua Gabb; Melania 
taylori Gabb; Oorbicula idahoensis Meek; JBytkmella, species inde- 
terminate; Fluminicola, species indeterminate but like Amnicola 
{Fluminicola) longinqua Gould, and fragments of Anodonta. The 
Anodonta shells occur whole in the deposits, but, on account of their 
extreme fragility, the specimens collected were much broken. 
From lake beds higher in the series than those from which the shells 
named above were obtained, well exposed in Little Valley, 9 miles 
west of Bruneau, internal casts of a large indeterminate species of 
Cannifex were obtained. 
While the precise position of these fossils in the geological time 
scale has not been determined, they are certainly of Tertiary age, and, 
as stated by Dall, probably belong to the Miocene. 
In the lake beds so well exposed in the northern portion of Owyhee 
County the frequent occurrence of fossil bones, some of them of large 
size, has been reported by ranchmen and others, but only a few indi- 
vidual bones and fragments of bones were collected. These were 
obtained from the surface portion of the lake beds exposed at the head 
of Little Valley, and although not sufficiently complete to permit 
specific determination, are stated b} T F. A. Lucas to consist of "a 
portion of the left scapula of a large camel, one of the toe bones of 
a small camel, and a toe bone of Morotherium." a Besides these 
mammalian remains, the vertebra, teeth, etc., of a fish related to the 
carp, Anchybopsis fasciolatus Cope, and the vertebra of a salmonoid 
fish, of the genus Rhabdofario Cope, were found in considerable num- 
bers. In reference to the age of these fossils Lucas says: "They are 
all typical Pliocene species, such as are found in the Pliocene of 
Washington, Oregon, and Idaho." 
Although the number of vertebrate remains obtained was small 
and of little scientific interest, there are indications, especially in the 
admirable state of preservation of the bones, that the beds from which 
they came will yield most important results in this connection when 
carefully searched. 
At a locality near the head of Little Valley and in soft white lake 
beds belonging to the same formation as the neighboring layers from 
a An early representative of the Edentates, including Megatherium, etc., which inhabited both North 
and South America in post-Tertiary times, and are remotely related to the living sloths and armadillos. 
