nature of animals, the more we perceive that the indication of instinct is the more certain way to judge of them. By the most attentive examination of the interior parts we only discover slight differences. The horse and ass, though they have a most perfect resemblance in the internal parts, are, nevertheless, animals of very different natures. The bull, ram, and goat, differ but little in their internal formation, though they form three species more distant than the horse and the ass; and the same observation holds with respect to the dog, the fox, and the wolf. The inspection of the external form shews this more clearly; but as in many species, especially in those the least distant, there is even in the exterior much more resemblance than difference, this inspection is not sufficient to determine whether they are of the same or different species; and when the shades are still less we can only combine them with the agreements they have with instinct. It is from the disposition of animals that we should judge of their natures; if we suppose two animals quite the same in their forms, yet different in their dispositions, they would not copulate nor breed together, and however much alike they would therefore be two distinct species. _Engraved for Barr's Buffon_ [Illustration: FIG. 44. _Shock Dog_] [Illustration: FIG. 45. _Lion Dog._] The same means to which we are obliged to have recourse to judge of the difference of neighbouring species, is what we ought still more to employ when we would distinguish the numerous varieties which take place in the same species. We know of thirty varieties in the dog, and yet it is certain that we are not acquainted with them all. Of these thirty there are seventeen which may be said to be owing to the influence of climate, namely, the shepherd's dog, the wolf dog, the Siberian dog, the Iceland dog, the Lapland dog, the mastiff, the common greyhound, the great Dane, the Irish hound, the hound, the harrier, the terrier, the spaniel, the water-dog, the small Dane, the Turkish dog, and the bull-dog. The thirteen others, which are the mongrel Turkish dog, the greyhound with hair like a wolf, the shock dog, (_fig. 44_) or lap dog, the pug dog, the bastard pug dog, the Calabrian, Burgos, and Alicant dogs, the lion dog, (_fig. 45._) the small water dog, the Artois dog, and the King Charles's dog, (_fig. 46._) are nothing but mongrels which proceed from the first seventeen races; and by tracing these mongrels back to the two races from which they issue their natures will be easily known but with respect to the first seventeen races, if we would know what relation there is among them we must attend to their instincts, forms, and many other circumstances. I have put together the shepherd's dog, the wolf dog, the Siberian, the Lapland, and the Iceland dogs, because there is a more striking resemblance between them than any others, in their forms and coats, and because they have all pointed noses somewhat like the