These mounds are sometimes inconspicuous, but generally somewhat elevated above the common surface, though rarely to the height of eighteen inches. Their form is that of a truncated cone, on a base of two or three feet, perforated by a comparatively large hole or entrance at the summit or in the side. The whole surface, but more particularly the summit, is trodden down and compacted, like a well-worn pathway. The hole descends vertically to the depth of one or two feet, whence it continues in an oblique direction downward. A single burrow may have many occupants. We have seen as many as seven or eight individuals sitting upon one mound. They delight to sport about the entrance of their burrows in pleasant weather; at the approach of danger they retreat to their dens; or when its proximity is not too immediate, they remain, barking, and flourishing their tails, on the edge of their holes, or sitting erect to reconnoitre. When fired upon in this situation, they never fail to escape, or if killed, instantly to fall into their burrows, where they are beyond the reach of the hunter. As they pass the winter in a lethargic sleep, they lay up no provision of food for that season, but defend themselves from its rigours by accurately closing up the entrance of the burrow. The further arrangements which the Prairie dog makes for its comfort and security are well worthy of attention. He constructs for himself a very neat globular cell with fine dry grass, having an aperture at top, large enough to admit the finger, and so compactly formed that it might almost be rolled over the floor without receiving injury. The burrows are not always equidistant from each other, though they occur usually at intervals of about twenty feet.[92]—JAMES. _Comment by Ed._ The scientific name of the prairie-dog is now _cynomys ludovicianus_; see Bradbury's _Travels_, in our volume v, note 61. [91] This description is drawn chiefly from a well-prepared specimen belonging to the Philadelphia museum, the tail of which, if we may decide from memory, is somewhat too short.