“This remarkable species, so much allied to the _Charadrius Wilsoni_, was scarcely seen by us for more than one or two days, and then on the central table-land of the Rocky Mountains, in the plains near the last of the streams of the Platte, pursued in our western and northern route. It being the month of July when we saw it, there is little doubt but that it was breeding in this subalpine region. The only individual shot, was seen skulking and running through the wormwood bushes which so generally clothe those arid and dry wastes. After running some time, it would remain perfectly still, as if conscious of the difficulty of distinguishing it from the colour of the grey soil on which it stood. All that we saw were similar to the present individual, and none, however flushed, took to the wing. We do not recollect hearing from it the slightest complaint or note of any kind, being intent probably on concealing its young or eggs by a perfect silence.” The skin from which I made my drawing was that of a female; and it is my opinion, that the male, when found, will have as distinct markings as those exhibited by _Charadrius melodus_ or _Ch. semipalmatus_. CHARADRIUS MONTANUS, ROCKY-MOUNTAIN PLOVER. _Townsend_, Journ. Acad. of Natural Sciences of Philadelphia, vol. vii. p. 192. Adult Female. Plate CCCL. Bill shorter than the head, straight, somewhat cylindrical. Upper mandible with the dorsal line straight to beyond the middle, then bulging a little and curving to the rather acute tip, which projects beyond that of the lower mandible, the sides flat and sloping at the base, convex towards the end. Nasal groove extended to the middle of the bill; nostrils basal, linear, open and pervious. Lower mandible with the angle rather short, the sides at the base sloping outwards: the dorsal line ascending and slightly convex, the edges sharp, the tip rather acute. Head of moderate size, oblong, the forehead rounded. Legs rather long and slender; tibia bare half an inch above the joint; tarsus slender, compressed, covered with angular scales, of which the anterior are much larger; toes short, slender, with numerous scutella above, marginate, the outer connected with the middle by a short membrane. Claws small, compressed, slightly arched, rather acute. Plumage soft, the feathers rather distinct on the upper parts, blended on the lower. Wings long and pointed; primary quills tapering, the first longest by a quarter of an inch, the rest rapidly graduated; inner secondaries tapering and elongated, one of them nearly as long as the outer primary when the wing is closed. Tail of moderate length, even, of twelve feathers.