I do not pretend to affirm positively that none of the animals which inhabit the warm climates are not common to both. To be physically certain of this it is necessary they should have been seen; but it is evident, with respect to the large animals of America, that none of them are to be found in the old continent, and very few of the small ones. Besides, allowing there to be some exceptions, they must relate to a trifling number of species, and in no degree affect the general rule which I intend to establish, and which seems to me to be our only certain guide to the knowledge of animals. This rule, which leads us to judge of them as much by climate and disposition as from figure and conformation, will seldom be found wrong, and it will enable us to avoid and discover a multitude of errors. If, for example, we mean to describe the hyæna of Arabia, we may safely affirm that it does not exist in Lapland; but we will not say with Brisson, and some others, that the hyæna and the glutton are the same animal; nor with Kolbe, that the crossed-fox, which inhabits the northern parts of the new continent, is found at the Cape of Good Hope, as the animal he mentions is not a fox, but a jackall. But it is not my object at present to point out all the errors of nomenclators; my intention is solely to prove that their blunders would have been less had they paid some attention to the differences of climates; if the history of animals had been so far studied as to discover, which I have done, that those of the southern parts of each continent are never found in both; and lastly, if they had abstained from generic names, which have confounded together a number of species, not only different, but even remote from each other.