Vast cities, with regularly laid streets, are often met with in extensive level spots on the prairie. The inhabitants are, however, not men, but creatures the size of a guinea-pig--rodents--a species of marmot. In their habit of associating together in communities, they put us in mind of the industrious beaver; but they are idle little fellows, evidently liking play better than work. Their heads are not unlike those of young terrier-pups, and their bodies are of a light brown colour. They have little stumpy tails, which, when excited, they constantly jerk up and twist about in a curious fashion. Their habitations are regular cones raised two or three feet above the ground, with a hole in the apex, which is vertical for the depth of two or three feet, and then descends obliquely into the interior. From the peculiar yelp or short squeaky bark which they give, the hunters call them prairie-dogs. In each separate community, which consists of many thousand individuals, there is a president dog, who seems to have especial charge of the rest. As a stranger approaches, the creatures who are out of their houses scamper back as fast as their legs will carry them, and concealing all but their heads and tails, utter loud barks at the intruder. This done, the greater number dive out of sight with a curious somersault, their little tails whisking in the air. The chief dog, and perhaps two or three other sentinels with him, remain on the tops of their houses barking lustily till the enemy gets within a few paces of them, when they also disappear, and the town remains silent and deserted. The traveller who wishes to observe their habits, by lying concealed and silent for a few minutes, may see after a time some little fellow pop his head out of his house, when he gives a few barks. It serves as a signal to the rest that danger has disappeared, and immediately the others emerge from their houses and begin to frisk about as usual.