190 THE HORSE AND ITS RELATIVES 



they ever ranged beyond it, although it may be 

 quite possible that some of the earlier extinct repre- 

 sentatives of the family were striped. It is true, 

 indeed, that certain prehistoric sketches from various 

 districts in France have been supposed to represent 

 zebras, for which one writer has even gone so far 

 as to propose the name Bquus rnaculatus. Pro- 

 fessor Boule ^ (in whose memoir fuller details on 

 this point will be found) has, however, pointed out 

 that the evidence is by no means conclusive, and 

 the representations of tliese so-called zebras may 

 be explained in three different ways. On one 

 hypothesis the zebra-like markings are merely 

 strokes employed by the artist to accentuate and 

 beautify his sketches. A second theory supposes 

 that all fossil horses, whether of the caballus, the 

 zebra, or the extinct stenonis type, were striped. 

 According to a third supposition it may be sur- 

 mised that true zebras existed in Europe during 

 the Pleistocene period, but that it has not been 

 found possible to distinguish their teeth and bones 

 from those of horses, onagers, and asses. 



Professor Boule, ^ who is in favour of the first 

 hypothesis, believes zebras to have taken origin 

 from the extinct Steno's horse {E. stenonis) of the 

 European Pliocene. 



The aforesaid Gravy's zebra {^Equus grevyi, 



' Annales de PaUontologie, vol. v. p. 133, 1910. 



* Bull. Soc. Ge'ol. de France, ser. 3, vol. xxvii. p. 537, 1899. 



