40 
the south. At the same time, the sorts are sometimes so nearly 
related as to make it certain that they once belonged to the 
same type. Still further, the large branches of that internal sea, 
such as the Madeira and the Negro, which are themselves mighty 
rivers, often produce the same zoological changes. This is par- 
ticularly observable in the quadrumana and in the gallinaceous 
birds. The dispersion of the different sorts of B aehyurus 
give a remarkable example of this fact. The immense range 
of the Andes has also produced similar effects, and sudden 
convulsions o.f nature, such as earthquakes, are known to 
have had the same consequences. By the same reason, the 
fresh-water fishes of the Amazonas and its mighty branches 
are, as a rule, of species different from those of the Parana 
and Paraguay, for all their head waters are sometimes only 
a mile or two distant one from the other ; and if this rule 
presents exceptions, I consider that they are due to accidental 
inundations that may from time to time unite smaller branches 
of these mighty streams. 
I submit these considerations with much humility, knowing 
with what animosity these questions are debated ; but they are 
the result of a whole life spent in zoological investigations in all 
parts of the world. I have for many years studied nature in 
nature itself. 
I cannot close these lines without expressing my best 
thanks to those who have assisted me. Sir Redmond Barry, 
to whom this Colony owes so much, granted me, by a most 
honourable exception, the loan of several Ichthyological books 
contained in the Public Library and missing in my own. Every 
naturalist knows that descriptions must be compared with speci- 
mens, and it is easy to understand how impossible it is to 
transport in a public establishment hundreds of preserved fishes 
which are often of large dimensions. I must also mention 
Professor McCoy, who did all in his power to assist me ; Dr. 
Black and Mr Le Souef, the President and Secretary of the 
Acclimatisation Society, who are always ready to devote their 
time and experience to any undertaking they consider useful to 
the Colony / to Messrs. Livington Rooke, Morton Alport, and 
Waterhouse, who have most kindly sent me valuable specimens 
from Hobart Town and Adelaide; to Messrs. Greorge Keesley 
