1833.) R. NEGRO TO R. COLORADO. 67 
on infusoria or confervee. Thus we have a little living world 
within itself, adapted to these inland lakes of brine. A minute 
crustaceous animal (Cancer salinus) is said* to live in countless 
numbers in the brine-pans at Lymington; but only in those in 
which the fluid has attained, from evaporation, considerable 
strength—namely, about a quarter of a pound of salt to a pint of 
water. Well may we affirm, that every part of the world is 
habitable! Whether lakes of brine, or those subterranean ones 
hidden beneath volcanic mountains—warm mineral springs—the 
wide expanse and depths of the ocean—the upper regions of the 
atmosphere, and even the surface of perpetual snow—all support 
organic beings. 
To the northward of the Rio Negro, between it and the inha- 
bited country near Buenos Ayres, the Spaniards have only one 
small settlement, recently established at Bahia Blanca. The dis- 
tance in a straight line to Buenos Ayres is very nearly five hun- 
dred British miles. The wandering tribes of horse Indians, 
which have always occupied the greater part of this country, 
having of late much harassed the outlying estancias, the govern- 
ment at Buenos Ayres equipped some time since an army under 
the command of General Rosas for the purpose of exterminating 
them. ‘The troops were now encamped on the banks of the Co- 
lorado; a river lying about eighty miles northward of the Rio 
Negro. When General Rosas left Buenos Ayres he struck ina 
direct line across the unexplored plains: and as the country was 
thus pretty well cleared of Indians, he left behind him, at wide 
intervals, a small party of soldiers with a troop of horses 
(a posta), so as to be enabled to keep up a communication with 
* Linnxan Trans., vol. xi. p. 205. It is remarkable how all the circum- 
stances connected with the salt-lakes in Siberia and Patagonia are similar. 
Siberia, like Patagonia, appears to have been recently elevated above the 
waters of the sea. In both countries the salt-lakes occupy shallow depres- 
sions in the plains; in both the mud on the borders is black and fetid; be- 
neath the crust of common salt, sulphate of soda or of magnesia occurs, im- 
perfectly crystallized ; and in both, the muddy sand is mixed with lentils of 
gypsum. The Siberian salt-lakes are inhabited by small crustaceous ani- 
mals; and flamingocs (Edin. New Philos. Jour., Jan. 1830) likewise frequent 
them. As these circumstances, apparently so trifling, occur in two distant 
continents, we may feel sure that they are the necessary results of common 
causes.—See Pallas's Travels, 1793 to 1794, pp. 129-134. 
