THE ARAB STOCK 161 



the bones are denser than in ordinary horses. The 

 latter feature was not, however, observable in an 

 American skeleton, although it may occur in desert- 

 bred Arabs. The features to which the greatest 

 importance are attributed comprise the sinuous 

 facial profile (due to a relatively large brain), the 

 absence of a sixth lumbar vertebra, the complete 

 shaft of the ulna, and the shortness of the tail, 

 which has sixteen in place of eighteen vertebrae. 

 As regards the completeness of the ulna, it is notice- 

 able that the same feature was observed in a 

 skeleton of Grevy's zebra. Taken together, the 

 foregoing distinctive features, in the opinion of 

 Professor Osborn, are sufficient to justify the specific 

 separation of the Arab, which appears to be de- 

 scended from ancestors distinct from those which 

 gave rise to the ordinary northern and western 

 horses. 



Fuller allusion has been made in a previous 

 chapter ^ to the preorbital depression in the skull 

 which appears to be characteristic of horses of the 

 Arab and Barb stock. It should be added that in 

 Arabs the cheek-teeth (pi. v. fig. 2) are relatively 

 small in comparison with the skull, and that the 

 upper premolars have their transverse diameter as 

 large as or larger than the longitudinal one, which 

 is not the case with the horses of Western Europe,^ 



^ Supra, p, 22. 



^ See Duerst, Animal Remains from Anau, p. 386. 



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