660 BOTANICAL INFORMATION. 
about the upper waters of Qui-court, Teton and Shyenne 
Rivers ; they seem to be likewise continuations of the easterly 
spurs of the Black Hills, and consist of vast ranges of 
bituminous shale, generally below the level of the great 
plains, but rising towards the river-valleys. They are cut 
into innumerable, very narrow and intricate, dark defiles or 
channels, with perpendicular sides about 150 feet in height, 
which absorb a brackish dark-brown water; otherwise they 
are analogous to those on the Missouri River, are capped 
with heavy dark loam, contain the same organic remains and 
picas of yellowish pumice stone strewed over their surface; 
and comprise about one half of the “ Burnt Hills" of Lewis. 
and Clark. There is nothing worth mentioning in their ve- 
getation, and these tracts are only interesting to the Geolo- 
gist, in so far as they indicate great part of the saline desert 
region. 
4th Sub-region.—Saline plains; the greatest portion of —— 
them in the immediate neighbourhood of the Black Hills; — . 
stretching round the base of the Rocky Mountains, and 
sloping off, interruptedly, towards S.S.E. A loamy crust, —— 
with the appearance of having been drifted, or an undulated- — 
crested surface, is the general character of the dry saline 
pleins. Large exsiccated flats, perfectly level, and often 
covered with a snowy white crust of soda; some exsi 
swamps being the exception. Swampy river-valleys only are 
covered with a luxuriant vegetation. uade 
The loamy portions of the dry saline plains are we 
centre of the Chenopodiacee in North America, and the 
habitat of Fremontia vermicularis, (Torrey), a many-stemme* 
shrub, from three to eight feet high, with somewhat horizontal _ 
branches, spinescent branchlets and dull-green succulent fo- 
liage. It firmly roots itself in the crest-like saline loam-banks, 
and collects by its many stems and intricate branches ut 
flying sands from the adjacent deserts. The young succulent - 
shoots are used by the trappers as a substitute for salt, and | 
at the same time for a vegetable, by boiling them with their - 
meat. On that account, and from a distant resemblance this 
