During the time of Captain Bell's absence on the excursion above detailed, observations were made at camp for latitude, longitude, &c., and all the party were busy in their appropriate pursuits. Among the animals taken here was the four-lined squirrel, (S. 4-vittatus, Say) a very small and very handsome species, very similar in its dorsal markings to the getulus, L.; but as far as we can judge from the description and figures of the latter species by Buffon,[16] our animal is distinguished by its striped head, less rounded ears, and much less bushy, and not striated and banded tail, and by its smaller size. The getulus is also said to have no thumb wart. It is an inhabitant of the Rocky Mountains about the sources of the Arkansa and Platte. It does not seem to ascend trees by choice, but nestles in holes and on edges of the rocks. We did not observe it to have cheek-pouches. Its nest is composed of a most extraordinary quantity of the burrs of the xanthium branches, and other portions of the large upright cactus, small {235} branches of pine-trees and other vegetable productions, sufficient in some instances to fill the body of an ordinary cart. What the object of so great, and apparently so superfluous an assemblage of rubbish may be, we are at a loss to conjecture; we do not know what peculiarly dangerous enemy it may be intended to exclude by so much labour. Their principal food, at least at this season, is the seeds of the pine, which they readily extract from the cones.[17] There is also another species[18] inhabiting about the mountains, where it was first observed by those distinguished travellers, Lewis and Clarke, on their expedition to the Pacific Ocean. It is allied to the Sc. striatus, and belongs to the same subgenus (tamias illig.) but it is of a somewhat larger stature, entirely destitute of the vertebral line, and is further distinguished by the lateral lines commencing before the humerus, where they are broadest by the longer nails of the anterior feet, and by the armature of the thumb tubercle. It certainly cannot with propriety be regarded as a variety of the striatus, and we are not aware that the latter species is subject to vary to any remarkable degree in this country. But the species to which, in the distribution of its colours, it is most closely allied, is unquestionably the Sc. bilineatus of Geoffroy.[19] A specimen is preserved in the Philadelphia Museum.