Rocky Mountains, 407 



field. From the great quantities of fresh earth recently 

 brought up, we perceived the little animals were engaged in 

 enlarging their subterranean excavations, and we watched 

 long, though in vain, expecting to see them emerge from 

 their burrows. It is probable the jarring of the earth under 

 the hoofs of our horses, by giving early notice of our ap- 

 proach, prevented them from appearing at the surface. 



In our way we passed the large hepatic spring visited by 

 Mr. Jessup, and described in his report. It rises in the bed 

 of a large brook, and diffuses a strong sulphurous odour 



they are separated by the common integument, they are profoundly con- 

 cave, opening downwards, and towards the mouth. 



The incisores which are not covered by the lips, but are alwa)'s exposed 

 to view, are strong and truncated in their entire width at tip; the superior 

 ones are each marked by a deep, longitudinal groove near the middle, and 

 by a smaller one at the inner margin. The molares, to the number of 

 eight in each jaw, penetrate to the base of their respective alveoles, with- 

 out any division into roots, as in the genus Arcicola, Lepus, &c. their 

 crown is simplydiscoidal, transversely oblong oval, margined by the enam- 

 el, and in general form they resemble the teeth of a Lepus, but without 

 the appearance either of a groove at their ends, or of a dividiog crest of 

 enamel; the posterior tooth is rather more rounded than the others, and 

 that of the upper jaw has a small prominent angle on its posterior face; 

 the anterior tooth is double, in consequence of a profound duplicature in 

 its side, so that its crown presents two oval disks, of which the anterior one 

 is smaller, and in the lower jaw somewhat angulated. All the molares of 

 the lower jaw incline obliquely forward, and those of the superior jaw ob- 

 liquely backward. 



The whole animal has a clumsy aspect, having a large head and body, 

 with short legs, large fore feet, and small hind feet; and although it walks 

 awkwardly, yet it burrows with the greatest rapidity, so that the difficulty 

 of obtaining specimens may be, in a great degree, attributed to the facility 

 with which the animal passes through the soil, in removing from the vicini- 

 ty of danger. 



They cast up mounds of loose earth, which, like those of the blind rat, 

 (Spalax typhlus) have no exterior opening. These elevations have been 

 aptly compared, by Lewis and Clark, to such heaps of earth, as would be 

 formed by the emptying of the loose contents of a flower-pot upon the soil. 

 The mounds are of various dimensions, from the diameter of a few inches 

 only, to that of several yards; the quantity of earth employed consequent- 

 ly varies from a pint to two or three bushels. 



So entirely subterraneau is the life of this animal that it is rarely seen; 

 and many persons have lived for many years surrounded by their little 

 edifices, without knowing the singular being by whose labours they are 

 produced. 



Itis known by the names of sand rat, goffer, pouched-rat, salamander, $c. 



