ORGANIC EVOLUTION 357 



It is believed that in still older rocks a five-toed form will be 

 discovered, which was the parent of the four-toed form. 



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 modem 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 modem 

 horse, and Fig. 106 some of the modifications through which 

 it has passed. Fig. 107 shows a reconstruction of the ances- 



