furnished evident proofs that it has been strongly volcanic, even at a very recent date, for the surface is still covered with lava and scoriae. I counted as many as seventy conical hills, from 2o to 150 feet in height, grouped in one single plain and in the space of from four to five miles: they had evidently gone through the ordeal of fire. Some of these hills were composed of cinders that the earth in her fiery convulsions appeared to have vomited from her center. Several times, after having gained some miles on the heights, we found ourselves suddenly facing an almost perpendicular descent, formed of rock and white clay, down which we had to let our vehicles by hand. We then entered into a chain of valleys and fertile prairies watered by springs and rivulets, and embellished with the cottonwood, elm, ash, cedar and pine; in other places the summits of the hills are remarkable for their beauty, and the rich undulating plains for their abundant verdure.
On the fourth day of our march we descried thousands of buffalo; the whole space between the Missouri and the Yellowstone was covered as far as the eye could reach. Hitherto the mosquitoes had greatly tormented us, but now they entirely vanished. We sought the cause of this phenomenon. The Indians told us that the absence of our winged enemies was owing to the prodigious number of buffalo which were grazing in the neighboring plains, and which attracted these insects. In fact, we saw these noble animals throwing the earth on their bodies by means of their horns and feet, or rolling themselves in the sand and dust, and thus filling the air with clouds, in the endeavor to rid themselves of their vexatious followers. The lot of these animals appeared bad enough, for they were pursued day and night. During a whole week we heard their bellowings like the noise of distant thunder, or like the murmurs of the ocean waves beating against the shore. It may be said that it is the country in which the buffalo and herds of deer are generally found -in the greatest abundance. A good hunter might easily kill here, in the course of a day, several cows, 42