22 
RIO DE JANEIRO 
CHAP. 
tricate wilderness of lakes ; in some of which were fresh, in 
others salt water shells. Of the former kind, I found a Limnsea 
in great numbers in a lake, into which the inhabitants assured 
me that the sea enters once a year, and sometimes oftener, and 
makes the water quite salt. I have no doubt many interesting 
facts in relation to marine and fresh-water animals might be 
observed in this chain of lagoons which skirt the coast of Brazil. 
M. Gay 1 has stated that he found in the neighbourhood of Rio 
shells of the marine genera solen and mytilus, and fresh-water 
ampullariae, living together in brackish water. I also fre¬ 
quently observed in the lagoon near the Botanic Garden, where 
the water is only a little less salt than in the sea, a species 
of hydrophilus, very similar to a water-beetle common in the 
ditches of England : in the same lake the only shell belonged 
to a genus generally found in estuaries. 
Leaving the coast for a time, we again entered the forest. 
The trees were very lofty, and remarkable, compared with those 
of Europe, from the whiteness of their trunks. I see by my 
notebook, “ wonderful and beautiful flowering parasites,” invari¬ 
ably struck me as the most novel object in these grand scenes. 
Travelling onwards we passed through tracts of pasturage, much 
injured by the enormous conical ants’ nests, which were nearly 
twelve feet high. They gave to the plain exactly the appear¬ 
ance of the mud volcanoes at Jorullo, as figured by Humboldt. 
We arrived at Engenhodo after it was dark, having been ten 
hours on horseback. I never ceased, during the whole journey, 
to be surprised at the amount of labour which the horses were 
capable of enduring ; they appeared also to recover from any in¬ 
jury much sooner than those of our English breed. The Vam¬ 
pire bat is often the cause of much trouble, by biting the horses 
on their withers. The injury is generally not so much owing to 
the loss of blood, as to the inflammation which the pressure of the 
saddle afterwards produces. The whole circumstance has lately 
been doubted in England ; I was therefore fortunate in being 
present when one (Desmodus d’orbignyi, Wat.) was actually 
caught on a horse’s back. We were bivouacking late one 
evening near Coquimbo, in Chile, when my servant, noticing 
that one of the horses was very restive, went to see what was 
the matter, and fancying he could distinguish something, 
1 Annales des Sciences Naturelles for i 833 - 
