ANCON SIN SALIDA. 578 
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 afew 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 difference at once distinguishable by the form 
VoL. I. 2P 
