themselves. I should not think that these interior sounds are much frequented by them; a family was, however, met in the Fitzroy Channel (which separates the Otway from the Skyring), clothed with guanaco skins, like the Patagonian tribes, but in manners and disposition resembling the wandering inhabitants of the Strait and Tierra del Fuego; and they had canoes, which the Patagonians do not use. They had probably come thus far for the purpose of communicating with the latter tribes, with whom they frequently have friendly intercourse. No guanacoes were seen either on the shores of the inland waters or of the sounds within the 'Ancon sin salida,' although the country, being open and covered with luxuriant grass, was peculiarly suited to their habits; but as several large herds of deer were observed feeding near the sea-shore of Obstruction Sound, and the neighbouring country, the presence of these latter animals may probably be the cause; for on the eastern coast, where the guanacoes are everywhere abundant, the deer do not make their appearance. Sea-otters were the only other animals that we met with, and they were only occasionally noticed swimming about the kelp. The shores of the sounds were in many places crowded with the black-necked swan (Anas nigricollis, Linn.), and there were a few seen, but only one captured, whose plumage, excepting the tips of the wings, which were black, was of a dazzling white colour. I have described it in the first part of the Proceedings of the Zoological Society as a new species (Cygnus anatoïdes.)
The Strait of Magalhaens, being a transverse section of the continent, exhibits a very good view of its geological structure. The strait may be divided into three portions; the western, central, and the eastern. The western end and centre are of primitive character, rugged and very mountainous; whilst the eastern portion is of recent formation and low. The western tract is composed of a succession of stratified rocks, a difference at once distinguishable by the form and nature of the ranges, and the direction of the shores; the hills are irregularly heaped together; the sounds are intricate and tortuous in their course, and the shores are formed by deep sinuosities and prominently projecting headlands: the channels, also, are studded with innumerable islands and rocks, extremely dangerous for navigation. In this portion the rock is, for the most part, granite and greenstone.
Near the centre of the Strait, the rock being clay-slate, the mountains are higher, and more precipitous and rugged in their outline; and consequently not easily to be ascended. They are in general three thousand feet, but some are found to be four thousand feet in height; and one, Mount Sarmiento, is upwards of six thousand feet high, and is covered throughout the year with snow. The line of perpetual snow in the Strait seems to be about
