ACANTHOPTERYGII Entire No. of species 82 whereof new 41
MALACOPTERYGII 39 25
LOPHOBRANCHII 3 3
PLECTOGNATHI 12 5
CYCLOSTOMI 1 1
—— ——
GRAND TOTAL 137 GRAND TOTAL, NEW 75
It appears from the above table that of the entire number of species,
three-fifths belong to the Acanthopterygian fishes,—rather more than
one-fourth to the Malacopterygian,—and about one-eighth to the remaining
orders united.
In the Acanthopterygians, the _new_ species amount to one-half; in the
Malacopterygians, to about two-thirds; in the remaining orders together,
to rather more than one-half.
Looking, therefore, to the entire number of species described, the
Acanthopterygians prevail; and it is in the same order that there are
most new ones: but looking to the proportion, which in each order the
new ones bear to the entire number, it is among the Malacopterygians
that this proportion will be found highest.
Restricting our view, it will be also seen, in the Malacopterygians,
that the new species are relatively most numerous in the fresh-water
groups, such as the _Siluridæ_, the _Cyprinidæ_, and _Salmonidæ_, in
which three families taken together, they amount to five-sixths of the
whole. The _Clupeidæ_ 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 _Siluridæ_, the
_Cyprinidæ_, and _Salmonidæ_, are from South America, and the Falkland
Islands, excepting one from New Zealand.
Of the remaining fresh-water fishes in the collection, three out of five
are presumed to be new. One of these is a species of _Perca_, from the
Santa Cruz river, in South Patagonia; the second is a species of
_Dules_, from the river Matavai, in Tahiti; 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 remark 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 _Sciænidæ_,
from the Galapagos Archipelago;—one to the _Scombridæ_, from North
Patagonia;—three to the _Blennidæ_, whereof one is from the Archipelago
of Chiloe, the second from the Falkland Islands, and the third from New
Zealand;—one to the _Cyprinidæ_, embracing three species, from South
Patagonia, Tierra del Fuego, and New Zealand; and, lastly, one to the
_Salmonidæ_, 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.
SERRANUS 3 species Fam. PERCIDÆ. ACANTHOPTERYGII.
PRIONOTUS 1 „ —— TRIGLIDÆ. „
SCORPÆNA 1 „ —— SCORPÆNIDÆ. „
PRIONODES _N.G._ 1 „ —— SCIÆNIDÆ. „
PRISTIPOMA 1 „ „ „ „
LATILUS 1 „ „ „ „
CHRYSOPHRYS 1 „ —— SPARIDÆ. „
GOBIUS 1 „ —— GOBIDÆ. „
COSSYPHUS 1 „ —— LABRIDÆ. „
GOBIESOX 1 „ —— CYCLOPTERIDÆ. MALACOPTERYGII.
MURÆNA 1 „ —— ANGUILLIDÆ. „
TETRODON 2 „ —— TETRODONTIDÆ. PLECTOGNATHI.
——
15
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, in 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 different 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 _continue to hold
a false position_ in the system, as _spurious_ species. They may not be
new, or they may not be species at all,—but they will be _known_; and
any mistake which has been committed will be at once rectified,—any new
name which has been wrongly imposed, immediately degraded to a synonym.
Accordingly I have been careful in this respect; and I have in some
instances, given full descriptions, even of species which are certainly
not new, but which I did not find described by previous authors with all
the detail that was requisite for completely identifying them; or,
leaving out what they have noticed, I have added such characters as they
have omitted. My main object has been to render all the species, whether
rightly named or not, easily recognizable; and, however little the
science may be advanced by what is brought forward, to make that
advance, so far as it goes, sure.
The method of description, and the mode of computing the fin-ray
formula, will be found conformable to the plan adopted in the “Histoire
des Poissons” of Cuvier and Valenciennes; a work which, in so many
respects, must always serve as a model to labourers in this department
of zoology.
The colours, in the great majority of instances, were, fortunately,
noticed by Mr. Darwin in the recent state. The nomenclature employed by
him for the purpose is that of Patrick Syme; and he informs me, that a
comparison was always made with the book in hand, previous to the exact
colour in any case being noted. Where I have observed any markings left
unnoticed by Mr. Darwin, I have added them myself; and, in most
instances, I have given the general disposition of the colours as they
appear in spirits, from the circumstance of their being often so much
altered by the liquor, and liable to mislead those, who have only the
opportunity of seeing them in preserved specimens. This is what Cuvier
and Valenciennes have frequently done in their work; and from them I
have borrowed the practice.
In a work of this nature, it has not been thought desirable to enter
into any discussion of the principles of scientific arrangement, or to
effect any change in systems already received; its main object being the
description of species. For this reason, I have taken the groups almost
exactly as they stand in the “Histoire des Poissons” of Cuvier and
Valenciennes, or in the “Regne Animal” of the former: yet there is
reason to believe that many parts of their system will be found
hereafter to require some modification, especially in regard to families
and genera which have for their distinctive character the presence or
absence of vomerine or palatine teeth. The small value which is to be
attached to such character is pointed out in some instances in the
following work, and much dwelt upon.
In conclusion, it may be stated, that the whole of the species in the
collection of fish brought home by Mr. Darwin, described in the
following pages, have been deposited by him in the Museum of the
Philosophical Society of Cambridge. They are mostly in spirit, and,
generally speaking, in a good state of preservation; some few, however,
are in the state of skins only, and have been mounted.