« PředchozíPokračovat »
the more modern and expressive one of Rodentia. To the seventh, the proper appellation, Ruminantia, is applied in the preface, but in the body of the work, this is discarded for Pecora ; and so, also, Cetacea in the preface becomes Ceta in the sequel. There does not appear to be any sufficient reason for thus retaining the Linnæan names of a few of the orders, whilst their constitution, and the names also of all the others, are adopted from a different system. Names themselves are not originally of any very great consequence, yet they become so, when they have been employed for a long time to designate particular things. It is not, perhaps, in itself a matter of much importance, whether the first order of Mammalia be denominated Primates, or Bimana ; but since it is generally known that the naturalists, who have severally adopted these names, constituted the order in a manner entirely different; that Cuvier places in it man alone, whilst Linnæus associated him with monkeys, lemurs, sapajous, and bats; the terms are gradually understood in a specific sense, and bear always the meaning attached to them by those, who first introduced them. At all events, the adoption of any new method of arrangement, or the use of any terms in a sense differing from that generally received, should be premised by some sufficient explanation.
It is stated in the preface, that 'twentyfive species are common to both continents, without including the cetaceous animals. That is to say, about one fifth part of the quadrupeds, inhabiting North America, are common to it with the Eastern continent. Dr Harlan is too ready to admit the identity of species of the new, with others of the old world, or at least he does it without showing that deliberation, which the decision demands, and without apparently considering the doubts, which rest upon the subject. It certainly admits of a doubt, whether any species of animals is common to the two continents, except where it may have been transported from one to the other, by some accidental mode of conveyance, or unless it resides in the northern regions, and is capable of enduring the rigors of a polar winter, so that it may be supposed to have passed in some way from one continent to the other.
It is a general result of the observations, upon the distribution of both the vegetable and animal creation, that each
species appears originally to have inhabited some particular region, from which it has spread more or less extensively, according to its own nåture, and the nature of the country in which it was first placed. Buffon remarked, that the animals of the old world were in general different from those of the new, and that the species common to both were such, as are able to endure the extreme cold of the arctic regions, and may therefore be supposed to have found a way from one continent to the other, where they approach very near together, and may have been formerly joined. Of the general truth of this statement, there is abundant proof. Whether there are not many individual exceptions is not so easily deterinined. All the largest, the most clearly described, and the most easily distinguished animals of the old world, are certainly peculiar to it; and although there inay be in the new, animals closely resembling them, corresponding to them, and often mistaken for them, yet they are almost always specifically, and often generically distinct. Thus of the Proboscidean family, the living elephants are peculiar to the eastern continent; and fossil remains indicate the former existence in the western, of a race of animals resembling them in many important particulars, although generically distinct; whilst there is sufficient evidence, that a species of elephant, adapted by its structure to endure the cold of the northern regions, formerly existed in both. of the celebrated ferocious animals of the feline race, we have not one. It is true we hear of the American tiger, and the American lion, but they are manifestly creatures smaller, less powerful, and less terrible. The wolf, on the contrary, whose constitution is hardy, and able to endure the rigors of a polar winter, is the same in Europe, in Asia, and in America. The two species of camel are confined to Asia and Africa. America has a genus, the Llamas, nearly allied, and not less adapted to the peculiar character of the countries in which it resides. The comparison might be carried farther, and it might be shown, that those species, which have been supposed common, have been small, obscure, imperfectly observed, not easily recognised, and incapable of that precise description, which may be given of the larger.
In confirmation of the same general view, it appears that the successive discovery of new and insulated portions of the globe, as America and New Holland, has brought to light, not only new genera and species, but races of animals of a totally different kind, possessing strange, and before inconceivable characteristics. Thus, on the discovery of America, were first known those singular animals, the sloths, characterised by Buffon as defective monsters, and rude and imperfect attempts of nature; and the marsupial animals, which were then looked upon as strange and anomalous, in their structure and habits. In New Holland an entirely new order of things was opened to the eyes of naturalists. The world of nature, in that remote region, seemed to have been formed upon a new model. The marsupial animals, before considered as exceptions to the general rules of anjinal conformation, were here found to predominate. Elsewhere regarded as rarities, here there was little else, till, as exceptions to these exceptions, to the infinite disturbance of all quiet and old fashioned naturalists, the monotremous genera, and among then that strange beast, the ornithorhynchus, were brought to light; a tribe of animals, that seem to scorn classification, set rule and order at defiance, and although properly neither flesh, fowl, nor reptile, yet bear such resemblance to each, as to puzzle any one who shall attempt to fix their place in the system of nature.
Another fact to the same purpose is, that of the various animals which inhabit the arctic regions, and whose constitution renders it impossible for them to bear the journey across the tropics, probably not one is found in the antarctic. This is not only true of the land animals, but also of those inhabiting the sea, from the largest, down to the most minute and inconsiderable. It is remarked by MM. Peron and Le Sueur, that upon an examination, not merely of the Dorides, the Aplysias, &c. but carried down to the Holothurias, the Actinias, and the Medusas, or even still farther to the sponges, universally regarded as occupying the lowest rank of animal existence, it is found that out of the whole immense multitude of these antarctic animals, not one is known in the northern seas.
Dr Prichard, a most intelligent English writer, has given the subject a full consideration in his Researches into the Physical History of Man,' a work full of learning and ingenuity. After an examination of all the instances in which it
might be supposed, that species were common to the eastern and western continents, he arrives at the conclusions, that no animal is common to the warm parts of the two continents; that no European species is indigenous in both, which is not a native of countries north of the Baltic in one, and of Canada in the other; that no Asiatic species is found in America, except such as inhabit the northern parts of the Russian empire, and most of these in those districts which approximate to America, whilst some bave left proofs of their existence there in their fossil remains, and some have even been traced through the intervening islands; and that scarcely any animal has an extensive range in the northern regions of either continent, wbich is not common to both. All these considerations point to the general inference, that these tribes are common to the two continents, because, from their locality and habits, they have been enabled in some way to effect a communication from one to the other ; but that, originally, each continent had its peculiar stock of mammiferous animals, which has continued peculiar in all parts of the continents, except where such a communication may be conceived, in the course of ages, to have taken place.
It therefore appears highly probable, that, with the limitations made above, the species aboriginal in each continent are also peculiar to it. And although this may not be conclusively established, the result at least is inevitable, that it behoves naturalists to be very cautious in admitting the identity of American and foreign species; that it should not be done except after a thorough examination of both external and internal characters, and then only by the concurrent opinion of competent judges.
Dr Harlan is unfortunate in the connexion and arrangement of his species, particularly in the subdivisions of tribes, families, and subgenera. He in no place directly informs us, whose system of subdivisions he has adopted. In a work confined to the animals of a particular country, we can of course have only parts of a methodical arrangement, but it is of little use to introduce these parts, when the student has no clue, by which to discover what and where is the whole to which they belong. Divisions of this sort have no use or meaning, except in relation to one another. Class, order, genus, and species, are terms universally received and authorised by long use; their extent and meaning are generally understood. But suborder, family, tribe, and subgenus, not to say section and division, are terms whose signification is by no means accurately defined. They are too often used in a vague sense, and by different authors in a very different one. There is a considerable uniformity in the arrangement of the animal kingdom, by naturalists, into the divisions of the first kind; they have proceeded commonly upon similar principles, and have arrived at results not very unlike. But with regard to the second kind, much diversity occurs, both in the principles by which authors have been governed in making them, and also in the meaning of the terms used to express them.
A beginner in natural history would be perpetually perplexed, and be liable to constant error, from the want of attention to this point, in the Fauna Americana. This work may be likely to fall into many such hands, and be taken as a guide in the study of this branch of science. It should, therefore, have been carefully guarded. How careless and superficial the author has been in this very particular, we proceed to show by a variety of examples.
The order, Carnivora, he subdivides into families according to Cuvier. The first family is that of Cheiroptera, containing animals of the bat kind. This family, as it appears, he subdivides into tribes, and immediately announces, without preparation, Tribe Vespertilio.' Under this tribe, after inserting and describing the genus Rhinopoma, he introduces the genus Vespertilio, with which he gives the dental formula of Linnæus and Desmarest, marked 1 and 2, implying, as one would imagine, that reference was made to two subdivisions of the genus, but whether this was intended, or whether the formulæ were introduced merely for the purpose of comparison, does not appear, and we are left in doubt what use to make of them. Then follows the generic description, and one species numbered 1. Immediately after the description of this species, a new division comes upon us unexpeciedly, entitled : 1st Division, Vespertilio, Geoff,' with a dental formula differing slightly from that of Desmarest, a short description, and an enumeration of the species hitherto observed. Three species of Vespertilio are then described, which, without reference to that already described,