INTRODUCTION. 
Tue number of species of Fish described or noticed in the following Part of the 
Zoology of the Beagle, amount to 137. It is right to observe that, judging from 
Mr. Darwin’s manuscript notes, relating to what he obtained in this department, 
this is probably not more than half the entire number which he collected. 
Unfortunately a large portion of the valuable collection sent home by him arrived 
in this country in too bad condition for examination, and was necessarily 
rejected. 
The localities visited by Mr. Darwin, and at every one of which more or fewer 
species of fish were obtained, were the Cape Verde Islands,—the coast of 
Brazil, including the mouth of the Plata, together with several inland rivers and 
streams in that district,—the coasts of Patagonia, and the Santa Cruz river,— 
Tierra del Fuego and the Falkland Islands,—the Archipelago of Chiloe,—the 
coasts of Chile and Peru,—the Galapagos Archipelago,—Tahiti,—New Zealand, 
King George’s Sound in Australia,—and, lastly, the Keeling Islands in the 
Indian Ocean. The great bulk of the species, however, are from the coasts, east 
and west, of South America. 
The particular locality assigned to each species respectively in the following 
work may be relied upon as correct ; pains having been taken by Mr. Darwin to 
affix a small ticket of tin, with a number stamped upon it, to each specimen, and 
to enter a note immediately in the manuscript catalogue, having the same number 
attached. In only three or four instances these tickets were found wanting, 
on the arrival of the collection in this country. 
A considerable portion of the species examined and described are new 
to science, especially of those collected in South America, and the adjoining 
Islands and Archipelagos. The new ones are supposed to amount to seventy-five 
at least, constituting more than half the entire number; and amongst these are 
apparently seven new genera. 
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