42 



THE PEJEVALSKY HOESE. 



Table of Measurements of the Cheek-teeth of the 

 Domestic Horse, the Asiatic Ass, and the Donkey. 



A. Upper Teetu. 



B. Lower Teeth. 



P. 

 P3 

 P4 

 M, 

 M., 

 M3 



E. caLallus. 

 No. 5,229. 



Length. 



28 

 24 



28 



Breadth, 



11 

 18 

 18 

 17 

 16 

 15 



E." hemionus. 

 No, 511. 



Length. 



32 

 27 

 26 

 24 



26 



Breadth, 



16 

 17 

 16 

 14 



13 

 12 



E. asinus. 

 No. 1,136. 



Length. 



22-5 



22 



20 



18 

 18 



Breadth. 



11 



15 



15 



14-5 



12 



10 



From these tables it is manifest that the dimensions of the 

 cheek-teetia, and the relation of the length of the wearing-surface 

 to its breadth, are the same in all species of Equus, and, there- 

 fore, cannot serve as distinguishing features, as Franck assumed.* 



Of much greater importance is another character mentioned by 

 Franck, in the same communication, as being of service in the 

 distinction of the teeth of the horse from those of the donkey. 

 This is the smaller degree to which the enamel of the teeth of 

 the ass are folded. The ass's teeth are also distinguished by the 

 absence of the so-called " spur," a projection into the anterior- 

 internal depression of the enamel (by which the anterior-internal 

 pillai' — Protoconus of Osborne — is separated from the posterior- 

 internal pillar — Hypoconus). The difference, in this respect, 



* Op. cit. p. 42. 



