INTRODUCTION.

The 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.

viIt may be interesting to state more particularly from what localities the new species principally come, and what proportion they bear to the entire number brought from each of those localities. Thus from Brazil about half are considered new;—from Patagonia at least half;—from Tierra del Fuego, the Falkland Islands, and the Galapagos Archipelago, all are new, without exception; and nearly all from Chiloe, and the coasts of Chile and Peru. Of the species brought from Tahiti, New Holland, and the Indian Ocean, not above one-fourth are new. This might have been anticipated from the better knowledge which we have of the Ichthyology of that quarter of the globe, than of South America.

It is much to be regretted that the portion of the collection which has been lost to science, was obtained in localities most abounding in novelties, judging from that portion of it which has been saved. Thus, not above five or six species will be found noticed in the following work, from Tierra del Fuego, where Mr. Darwin took especial pains to collect all he could, and, judging from his manuscript catalogue, he must probably have obtained between thirty and forty. From the Falkland Islands again, there have been only saved two out of fifteen or sixteen,—from the coasts of Chile and Peru, not half the entire number obtained, and not above half from the coasts of Patagonia.

There is also described not above half the species brought from King George’s Sound, and the Keeling Islands; but as the Indian and Australian species, or at least the former, have been more frequently brought to Europe than the South American, they are less to be regretted than these last.

It is fortunate that the whole of the species obtained by Mr. Darwin in the Galapagos Archipelago, amounting to fifteen, have been preserved, and are described in the following pages.

It may now be useful to mention, to what groups principally—first, the entire number of described species belong, and, secondly, that portion of them which are considered new. Both these points will be best judged of from the following table, in which the whole collection is parcelled out according to the families.

ACANTHOPTERYGII.

Percidæ Entire No. of species 18 whereof new 11

Mullidæ 3

Triglidæ 3 1

Cottidæ 2 2

Scorpænidæ 4 2

Sciænidæ 10 5

Sparidæ 1 1

Mænidæ 2

Chætodontidæ 2

Scombridæ 7 3

Teuthydidæ 2

Atherinidæ 3 2

Mugilidæ 3

Blennidæ 11 7

Gobidæ 3 2

Labridæ 7 5

Lophidæ 1

Total 82 Total, new 41

vii

MALACOPTERYGII.

Siluridæ Entire No. of species 3 whereof new 2

Cyprinidæ 7 6

Esocidæ 1

Salmonidæ 8 7

Clupeidæ 5 5

Pleuronectidæ 6 1

[probably more.]

Cyclopteridæ 2 2

Echeneididæ 1

Anguillidæ 6 2

[perhaps more.]

Total 39 Total, new 25

LOPHOBRANCHII.

Syngnathidæ Entire No. of species 3 whereof new 3

PLECTOGNATHI.

Tetrodontidæ Entire No. of species 7 whereof new 4

Balistidæ 5 1

Total 12 Total, new 5

CYCLOSTOMI.

Petromyzonidæ Entire No. of species 1 whereof new 1

TOTAL IN THE SEVERAL ORDERS.

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, viiithey 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

ixIn 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 xspecies. 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.

xiIn 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.

L. JENYNS.

Swaffham Bulbeck,

Jan. 8, 1842.

xiii