Narrative of the surveying voyages of his majesty's ships Adventure and Beagle (vol.1): between the years 1826 and 1836 : describing their examination of the southern shores of South America, and the Beagles's circumnavigation of the globe

ANCON SIN SALIDA, 573 ascertained. The eastern shores of the interior channels were found to be low plains, with no hills or mountains visible in the distance; and such being characteristic also of the northern shores of the Otway and Skyring Waters, it is probable that all the coun- try to the east of the sounds is a continued plain. Recent traces of Indians were seen in some places ; but at the time our party was there, they were either absent or had concealed themselves. I should not think that these interior sounds are much frequented by them ; a family was, however, met in the passage between the Otway and the Skyring Water, 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 every where abun- dant, the deer do not make their appearance. Sea-otters were the only other animals that we met with ; but they were only occasion- ally 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 cap- tured, 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 anatoides.^ The Strait of Magalhaens, being a transverse section of the continent, exhibits a view of its geological structure. The Strait may be divided into three portions ; the western, the central, and the eastern. The western and central are of primitive character, rugged and very mountainous ; but the eastern portion is of recent formation and low. The western tract is composed of a succession of stratified rocks, a diiference at once distinguishable by the form VOL. r. 2 p