356 The Naturalist Brazilian Expedition. [Apri 
or swampy plain extends to the ocean. The plain and the sandy 
islands in the lake are the resorts of many water-birds, white 
herons and ducks being particularly abundant. One species, called 
the pato ermino, or ermine duck, sometimes occurs in vast num- 
bers, completely covering the small islands; from this bird the 
_ lake has taken its name. The skins of the pato erminho, with the 
larger feathers rubbed or pulled out, furnish a substance resem- 
bling swans’ down; this is occasionally preserved by the Brazilians; 
but more as a curiosity than for use. It might be made a valua- 
ble article of export. t 
From Pelotas the steamers run directly to Porto Alegre, about 
twenty hours being occupied in the passage. The Lagoa dos 
Patos, through which our route lay, is the largest lake in Brazil, 
its length being over 130 miles, while its breadth varies from twee 
ty to thirty-five miles. On the western side it is very shallow, 
and the shores are there bordered by swamps, which extend i 
inland ; the only navigable channel is along the eastern side, sit 
ing the sandy peninsula which separates the lake from the ea 
The winds sweep in freely over these low sand-hills, and in stormy 
weather the lake is very rough; navigation is then decide 
gerous even for steamers. During the night we had a little taste r 
this in a heavy thunder-storm which broke over us, causing © 
small vessel to roll heavily; beyond this we suffered g: me j 
venience, and the storm soon passed; but to the immigrants í 
deck the night must have seemed a sorry introducti 
newly adopted country. 
At its northern end the lake is split into two parts; the pU 
one, bordering on the sand-dune region, receives sw 
streams ; the western is a wide, deep estuary, called the Rio’ 
hyba. The mouth of the Guahyba is marked by rocky pr 
either side, but the lake may be looked upon as a continuatio 
the river. More broadly speaking, the lake is a ge0 e 
has been formed by the joint action of the Guahyba andt et 
currents, probably during a period of subsidence. meee | 
of the lake is therefore similar to that of the sounds se | 
process has been carried farther ; the lake has become ©" wane 
pletely separated from the ocean, and its waters are we at 
have not personally examined the Lagoa Mirim, but there” 
