(L. rupestris), the seasonal changes of plumage of which were described above, is also found in Arctic America and in northern Asia as far as the Ural Mountains. In this country its nesting range extends from the Alaska peninsula and Bering Strait along the Arctic coast and through the Barren Grounds to the west coast of Hudson’s Bay and Labrador. Nelson, for example, found it to be a common resident of the Alaskan mainland, frequenting “the summits of the low hills and mountains during the summer season, where it remains until the severe weather of early winter forces it down to the lower elevations and under the shelter of the bush-bordered ravines and furrows.” In the vast Barren Grounds it is also at home, subsisting on seeds, berries, and buds, like its relative just described. The nest is said to be placed among the dwarf birches and willows, and on the sedge-covered tundras, the eggs varying in number from six to ten. A number of subspecies of this have been differentiated, as the Greenland Ptarmigan (L. r. reinhardti) of Greenland, the islands on the western side of Cumberland Gulf, and northern Labrador; Nelson’s Ptarmigan (L. r. nelson), of the island of Unalaska; Turner’s Ptarmigan (L. r. atkhensis), of the neighboring island of Atkha; and Evermann’s Ptarmigan (L. r. evermanni) of Attu Island, while the closely allied Welch’s Ptarmigan (L. welchi) is confined to Newfoundland. These forms are all very close and by some authorities are not accepted as valid, though no one who has carefully studied these birds but has easily been convinced of their distinctness.