It is true, that I have enjoyed all the advantages which were necessary for the undertaking; and that my favourable situation, in the Museum of Natural History at Paris, and assiduous research for nearly thirty years, have procured me skeletons of all the genera and sub-genera of quadrupeds, and even of many species in some genera, and of several varieties of some species. With such means, it was easy for me to multiply my comparisons, and to verify in all their details the applications which I have made of the various laws deducible from such circumstances as have been stated. We cannot here enter into a more lengthened detail of this method, and must refer to the large work on Comparative Anatomy, in which all its rules will be found. In the mean time, an intelligent reader may gather a great number of these from the work upon Fossil Bones, if he take the trouble of attending to all the applications of them which we have there made. He will see, that it is by this method alone that we are guided, and that it has almost always sufficed for referring each bone to its species, when it was a living species--to its genus, when it was an unknown species--to its order, when it was a new genus--and to its class, when it belonged to an order not hitherto established--and to assign it, in the three last cases, the proper characters for distinguishing it from the nearest resembling orders, genera, and species. Before the commencement of our researches, naturalists had done no more than this with regard to animals, which they had the opportunity of examining in their entire state. Yet, in this manner, we have determined and classed the _remains_ of more than a hundred and fifty mammiferous and oviparous quadrupeds. _View of the General Results of these Researches._ Considered with regard to species, upwards of ninety of these animals are most assuredly hitherto unknown to naturalists; eleven or twelve have so perfect a resemblance to species already known, that the slightest doubt cannot be entertained of their identity; the others exhibit many traits of resemblance to known species, but their comparison has not yet been made with sufficient precision to remove all doubts. Considered with regard to genera, of the ninety hitherto unknown species, there are nearly sixty that belong to new genera. The other species rank under genera or subgenera already known. It may not be without use, also, to consider these animals with regard to the classes and orders to which they belong. Of the hundred and fifty species, about a fourth part are oviparous quadrupeds, and all the rest mammifera. Of these last, more than the half belong to non-ruminant hoofed animals.