Rocky Mountains. 453 



between the jointsj are oblong and flattened, being longer 

 and thicker than a man's hand. A second species, the C. 

 mamillaris N. occurs on the dry sandy ridges between the 

 Pawnee villages and the Platte. The beautiful cristaria coc- 

 cinnea. Ph. (malva coccinnea. N.~) is very frequent in the 

 low plains along the Platte. Its flowers have nearly the as- 

 pect of those of the common wild rose, except that they are 

 more deeply coloured. 



We arrived at the Platte a little before sun-set, the dis- 

 tance from the Pawnees being, according to our computation, 

 twenty-five miles. After entering the valley of the river we 

 travelled several miles across an unvaried plain, and at length 

 passing down by a gradual descent of a few feet, we came 

 upon a second level tract, extending to the river. 



The soil of the first of these portions is a bed of sand, in- 

 termixed with small water-worn pebbles and gravel, that of 

 the latter is more fertile, and produces a luxuriant vegetation. 



Our guide informed us that the Platte, opposite the point 

 where we entered its valley, contains an island which is more 

 than one day's journey across, and about thirty miles in 

 length. 



of food for that season, but defend themselves from its rigors by accurately 

 closing up the eutrance of the burrow. The furthur arrangements which 

 the Prairie dog makes for its comfort and security are well worthy of at- 

 tention. He constructs for himself a v?ry neat globular cell with fine 

 drv 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.* 



* In these villages, where the grass is fed close, and where much fresh earth is 

 brought up and exposed to the air, is the peculiar habitat of a species of Sola- 

 tium approaching the S. Irlflorum of Nuttall, which he says occurs as a weed " about 

 the gardens of the Mandans and Minatarecs of the Missouri, and iu no other situa- 

 tions " It appears to differ from the S. triflorum in being a little hirsute, with flat, 

 ruueinate pinnatifid leaves, and the peduncles alternating with the leaves. The 

 Solanum heterandrum of Pursb, now referred to the new genus Androcera of Nut- 

 tall, is also very common, but is not confined, like the plant just mentioned, to the 

 marmot villages. We collected also the Psoralca cuspidata, Ph P. escutenta, N. 

 P. incana, N also a species of Hieracium — H. runcinatum. Plant hirsute, leaves all 

 radical, eliptic-oblong runcinate; scape few-flowered, somewhat compressed, and an- 

 gular, glands on the hairs of the calix, very small and diaphanous; about one foot 

 high; flower small. Hab. in depressed, grassy situations along the Platte. 



