In the collections at Yale College there are preserved upward of thirty steps or stages in the history of the horse family, showing that it arose by evolution or gradual change from a four-or five-toed ancestor of about the size of a fox, and that it passed through many changes, besides increase in size, in the two million years in which we can get facts as to its history. Remarkable as is this feature of the Marsh collection at New Haven, it is now surpassed by that in the Museum of Natural History in New York City. Here, through the munificent gifts of the late W.C. Whitney, there has been accumulated the most complete and extensive collection of fossil horses in the world. This embraced, in 1904, some portions of 710 fossil horses, 146 having been derived from explorations under the Whitney fund. The extraordinary character of the collection is shown from the fact that it contains five complete skeletons of fossil horses--more than existed at that time in all other museums of the world. The specimens in this remarkable collection show phases in the parallel development of three or four distinct races of horse-like animals, and this opens a fine problem in comparative anatomy; _viz._, to separate those in the direct line of ancestry of our modern horse from all the others. This has been accomplished by Osborn, and through his critical analysis we have become aware of the fact that the races of fossil horses had not been distinguished in any earlier studies. As a result of these studies, a new ancestry of the horse, differing in details from that given by Huxley and Marsh, is forthcoming. Fig. 105 shows the bones of the foreleg of the modern horse, and Fig. 106 some of the modifications through which it has passed. Fig. 107 shows a reconstruction of the ancestor of the horse made by Charles R. Knight, the animal painter, under the direction of Professor Osborn. [Illustration: Fig. 105.--Bones of the Foreleg of a Horse.] While the limbs were undergoing the changes indicated, other parts of the organism were also being transformed and adapted to the changing conditions of its life. The evolution of the grinding teeth of the horse is fully exhibited in the fossil remains. All the facts bear testimony that the horse was not originally created as known to-day, but that his ancestors existed in different forms, and in evolution have transcended several genera and a considerable number of species. The highly specialized limb of the horse adapted for speed was the product of a long series of changes, of which the record is fairly well preserved. Moreover, the records show that the atavus of the horse began in North America, and that by migration the primitive horses spread from this continent to Europe, Asia, and Africa. [Illustration: Fig. 106.--Bones of the Foreleg and Molar Teeth of Fossil Ancestors of the Horse. European Forms. (After Kayser.)]