they amount to five-sixths of the whole. The Clupeidw are an exception, in which
all the species are apparently new.
All the species described, belonging to the three families above mentioned, in
which there are so many new, viz. the Silurida?, the Cyprinida, and Salmonidee,
are from South America, and the Falkland Islands, excepting one from New
Zealand.
O f the remaining fresh-water fishes in the collection, three out of five are
presumed to be new. One of these is a species of Perea, from the Santa Cruz
river, in South P atagonia; the second is a species of Pules, from the river
Matavai, in T ah iti; the third a species of Atherina, from Valparaiso. Perhaps,
however, this last is not strictly an inland species.
The entire number of fresh-water species in the collection is twenty-three,
and the entire number of new ones amongst these is eighteen. The large
proportion of these latter is a circumstance in confirmation of a rem ark which
Cuvier has somewhere made, that the fresh-water fishes of foreign countries are
much less known and understood than those found on the coasts. It may serve
also as a hint to future travellers.
The seven new genera in the collection belong—one to the Scicenidw, from
the Galapagos A rchipelago;—one to the Scombridw, from North Patagonia;—
three to the Blennidw, whereof one is from the Archipelago of Chiloe, the second
from the Falkland Islands, and the third from New Z ealand;—one to the Cy-
prinidcB, embracing three species, from South Patagonia, Tierra del Fuego, and
New Zealand; and, lastly, one to the Sahnonidce, embracing two species from the
Falkland Islands and Tierra del Fuego respectively.
It has been already mentioned, that all the species obtained by Mr. Darwin
in the Galapagos Archipelago have been preserved. As they are likewise all
new, and those islands appear to have been scarcely visited by any naturalist
previously, it may be interesting to enumerate the several genera to which they
belong, and the number of species in each genus respectively.
S e r r a n u s
P r i o n o t u s
ScO R PffiX A . . . . 1
P r i o n o d e s N . G . 1
P r i s t i p o m a 1
L a t i l u s ................ 1
C h r y s o p h r y s .. I
G o b iu s ............... 1
C o S S Y P IIU S _____ 1
G o b ie s o x . . . I
i^TR®NA I
T e t r o d o n ------- 2
3 s p e c i e s .
i
Fam. P E R C ID J:.
TR IG L ID iE.
SCORPA:NID.ffi.
I SCIjE N ID ® .
— s p a r i d a :.
.— g o b id ;e .
L A B R ID ^ .
CY C L0PTER ID 7E.
A N G U IL L ID ^ .
TETRO D O N T ID iE.
A CA N TH O PTERY G II.
> M A LACOPTERYGII.
PLEC TO G N A TH L
In making the foregoing estimates, as regards the number of new species
brought home by Mr. Darwin, I have been guided almost entirely by my own
judgment. The difficulty, however, of ascertaining, in a miscellaneous collection
of this nature, brought from various localities, what are really new to science, is
very great; and this difficulty is much increased, where an author is situate apart
from large public museums to which he might have recourse for comparison.
Possibly, therefore, some of those described as new in the following work, may
not be so in reality; and, in one instance, as mentioned in the Appendix, this
is known to be the case. My excuse, however, must rest upon what has been
just stated. It is hoped that caution has been generally shown, at least in regard
to specimens not in a good state of preservation; and, in several such cases, iii
which an accurate description was hardly practicable,—though they could not be
referred to any known species,—they are not positively declared new, nor any
names imposed upon them whatever.
I have, of course, consulted throughout the invaluable volumes of Cuvier
and Valenciennes, so far as they have yet advanced in the subject; and in them
it will be found that a few species, brought by Mr. Darwin from South America,
and still but little known, had nevertheless been previously obtained from the
same country by M. Gay. The zoological atlasses of the three great French
voyages by Freycinet, Duperrey and D ’Urville have been also carefully looked
through ; and, in regard particularly to the fish of South America, the works of
Humboldt, Spix and Agassiz, and the more recent one, now in course of publication,
by M. D'Orbigny.
There is an equal difficulty felt by every naturalist at the present day, in
distinguishing species from varieties. And in the case of Fish, residing in a
peculiar element, and so much removed from our observation,—we are almost at a
loss to know, at present, to what extent their characters may be modified by
local and accidental causes, or how far we may trust a different geographical
position for giving permanence and value to a slight modification of form
difterent from what occurs in the species of our own seas. Still less easy is
it to determine the true importance of characters, in instances in which it
is only permitted to see a single specimen of the kind, or, at most, very few
individuals.
Many mistakes, therefore, are liable to occur, in a work of this nature, arising
from the above sources. The only way to prevent their creating any permanent
confusion in the science, is to describe all species of which the least
doubt is entertained, in such detail, and with such accuracy, that they may not
fail of being recognized by any observer, to whom they may occur a second time.
They will not then coniinue to hold a false position in the system, as spurious