KVOLUTIOX Ol- TTIK IIORSK. 123 



Glacial Period, but they also became extinct in Central and 

 South America, where there was no ice sheet, and survived in 

 Kurope until the Postglacial. But we might now be in a 

 horseless age indeed had not a sufficient number of species 

 survived in Asia and Africa to continue the line, and to-day 

 we have the horse, the ass and the zebra — three branches 

 that have come down to us from this prehistoric wild horse. 

 These descendants are still to be found in Asia, where we 

 have Przewalsky's Wild Horse, of which little is known, and 

 the Asiatic Wild Ass ; while in Northern Africa we have the 

 African Wild Ass, and in the south of that continent there are 

 several species of zebra. The so-called wild horses that until 

 recently roamed the plains of North and South America, were 

 feral, that is they were not truly wild, but were the descend- 

 ants of domesticated horses brought here by Europeans and 

 abandoned. That these three branches sprang from a remote 

 common parentage is pretty well proven by similarity in strip- 

 ing. The ass and zebra show the strong back stripe which 

 occasionall)' crops up in our domestic horses, the circular leg 

 stripes rarely showing in all three. A beautiful example of this 

 reversion recently came under the observation of the writer. 

 Among the farm animals at the Williamson School of Mechan- 

 ical Trades is a dun ( clay ) colored horse with not only the black 

 band from mane to tail exceptionally well marked, but with 

 seven distinct circular stripes upon each leg, conforming to 

 those of the zebra in their peculiar pattern. This community 

 of marking strengthens our presumption that, as the Tertiary 

 ancestors of the horse lived in an environment of sunlight 

 and shade, they were striped like the zebra, for this coloring- 

 makes less contrast in the sifting sunlight or moonlight of the 

 forest, and affords a degree of concealment against prowling 

 carnivora. But at present we have no means of telling at 

 what period this branching occurred that led away from the 

 stripes, though the change in both conformation and color 

 was undoubtedly tlue to change in environment. 



It is inferred that the Old World horses came from America 



