158 RIO PLATA. [cHAP. VIII. 
have been brought up by their unnatural parent, Spain, should 
always be borne in mind. On the whole, perhaps, more credit 
is due for what has been done, than blame for that which may be 
deficient. It is impossible to doubt but that the extreme liberalism 
of these countries must ultimately lead to good results. The very 
general toleration of foreign religions, the regard paid to the 
means of education, the freedom of the press, the facilities 
offered to all foreigners, and especially, as I am bound to add, to 
every one professing the humblest pretensions to science, should 
be recollected with gratitude by those who have visited Spanish 
South America. 
December 6th.— The Beagle sailed from the Rio Plata, 
never again to enter its muddy stream. Our course was directed 
to Port Desire, on the coast of Patagonia. Before proceeding 
any further, I will here put together a few observations made at 
sea. 
Several times when the ship has been some miles off the mouth 
of the Plata, and at other times when off the shores of Northern 
Patagonia, we have been surrounded by insects. One evening, 
when we were about ten miles from the Bay of San Blas, vast 
numbers of butterflies, in bands or flocks of countless myriads, 
extended as far as the eye could range. Even by the aid ofa 
telescope it was not possible to see a space free from butterflies. 
The seamen cried out “it was snowing butterflies,” and such in 
fact was the appearance. More species than one were present, 
but the main part belonged to a kind very similar to, but not 
identical with, the common English Colias edusa. Some moths 
and hymenoptera accompanied the butterflies ; and a fine beetle 
(Calosoma) flew on board. Other instances are known of this 
beetle having been caught far out at sea; and this is the more 
remarkable, as the greater number of the Carabide seldom or 
never take wing. The day had been fine and calm, and the one 
previous to it equally so, with light and variable airs. Hence 
we cannot suppose that the insects were blown off the land, but 
we must conclude that they voluntarily took flight. The great 
bands of the Colias seem at first to afford an instance like those 
on record of the migrations of another butterfly, Vanessa cardui ;* 
» Lycll’s Principles of Geoiogy, vol. ili. p. 63. 
