July 10th [9th]. A beautiful species of pigeon was shot near the mountain. The head is of a purplish cinereous colour; the back of the neck, and its sides, brilliant golden-green; the feathers at base brownish purple; above this patch, and at base of head, is a white semi-band; the under part of the neck is pale vinaceous purplish; this colour becomes paler as it approaches the vent, which, with the inferior tail coverts, is white; anterior portion of the back, the {199} wing coverts and scapulars are brownish ash; the larger wing feathers dark brown, approaching black; the exterior edges whitish; the lower part of the back, the rump and tail coverts, inferior wing coverts and sides, bluish ash; paler beneath the wings; the shafts of the body-feathers and tail coverts are remarkably robust, tapering rather suddenly near the tips; the tail is medial, rounded at tip, consisting of twelve feathers, a definite black band at two-thirds their length from the base, before which the colour is bluish ash, and behind it dirty whitish; the bill is yellow, tipped with black, and somewhat gibbous behind the nostrils; the irides red; the feet yellow; claws black. This species seems to be most intimately connected to the ring-tailed pigeon (C. caribæa), from which it differs in the colour of the legs and bill, and in not having the gibbosity at the base of the latter so remarkable. It is possible that it may be an intermediate link between the ring-tailed pigeon and the stock pigeon of Europe, with the latter of which it has, in common, the exterior white edging to the greater wing feathers. It may be distinguished by the name of band-tailed pigeon (columba fasciata, Say); and may be seen, with other specimens of natural objects collected on this expedition, in the Philadelphia Museum. Several of the tributaries to Defile creek appear to discharge as much water as is seen in the stream below their junction. This appearance is common to many of the larger creeks, their broad and sandy beds allowing much of the water to sink, and pass off through the sand. In the evening, a favourable opportunity, the first for several days, presented, and observations for latitude were taken. That part of Defile creek, near which we encamped, is filled with dams, thrown across by the beaver, causing it to appear rather like a succession of ponds than a continued stream. As we ascended {200} farther towards the mountains, we found the works of these animals still more frequent. The small willows and cotton-wood trees, which are here in considerable numbers, afford them their most favourite food.