races, thus carrying out the law of gradation in hybridity. If the mulattoes of New Orleans and Mobile be compared with those of the Atlantic States, the fact will become apparent. The argument in favor of unlimited prolificacy between species may be strongly corroborated by an appeal to the history of our domestic animals, whose history is involved in the same impenetrable mystery as that of man. M. Geoffroy St. Hilaire very justly remarks that we know nothing of the origin of our domestic animals; because we find wild hogs, goats, sheep, &c., in certain parts of Europe, several thousand years subsequent to the early migrations of man, this does not prove that the domestic come from these wild ones. The reverse may be the case.[209] We have already made some general observations on the _genus canis_, whose natural history is most closely allied to that of man. Let us now inquire whether the domestic dog is but one species, or whether under this head have been included many proximate species of unlimited prolificacy. If we try the question by _permanency of type_, like the races of men, and all well-marked species, the doubt must be yielded. There are strong reasons given by Dr. Morton and other naturalists, for supposing that our common dogs, independent of mixtures of _their_ various races, may also have an infusion of the blood of foxes, wolves, jackals, and even the hyena; thus forming, as we see every day around us, _curs_ of every possible grade; but setting aside all this, we have abundant evidence to show that each zoological province has its original dog, and, perhaps, not unfrequently several. In one chapter on hybridity in the "_Types of Mankind_," it is shown that our Indian dogs in America present several well-marked types, unlike any in the Old World, and which are indigenous to the soil. For example, the Esquimaux dog, the Hare Indian dog, the North American dog, and several others. We have not space here to enter fully into the facts, but they will be found at length in the work above mentioned. These dogs, too, are clearly traced to wild species of this continent. In other parts of the world we find other species equally well marked, but we shall content ourselves with the facts drawn from the ancient monuments of Egypt. It is no longer a matter of dispute that as far back, at least, as the twelfth dynasty, about 2300 years before Christ, we find the common small dog of Egypt, the greyhound, the staghound, the turnspit, and several other types which do not correspond with any dogs that can now be identified.[210] We find, also, the mastiff admirably portrayed on the monuments of Babylon, which dog was first brought from the East to Greece by Alexander the Great, 300 years B. C. The museums of natural history, also, everywhere abound in the remains of _fossil_ dogs, which long antedate all living species.