THE PEJEVALSKY HOESE. 43 



between the molar teeth of the horse and the ass is clear from 

 the drawings accompanying Franck's paper. The folding of the 

 anterior and posterior crescentic ridges of enamel is much more 

 sharply jironounced in the horse than in the ass. In this particular 

 E. 'prjevahJcii undoubtedly stands near to the domestic horse. 

 Though the absence of the so-called " spur " is very clear in the 

 donkey and the Asiatic ass, its presence and strong development 

 are characteristic for neither E. cahallus nor E. prjevalskii. 

 Among the skulls in the collection of the Zoological Museum, the 

 "spur" is distinct in No. 5,231 (a horse from the Derbet) ; but 

 in all other skulls, on the contrary, it is either small or entirely 

 absent. Among the skulls of the Prjevalsky horse, there is a 

 A^ery long fold, representing the " spur," in No. 5,218 ; in Nos. 



5.212, 5,214 and 5,216, the fold is feebly developed ; and, in No. 



5.213, it is completely wanting. 



THE VERTEBRAL COLUMN AND THE BONES OF THE 

 LIMBS. — In contrast to the fairly large number of tlie skulls of 



P"ig. II. — Atlas (ventral aspect). 



E. 'prjevalskii, the Zoological Museum contains only one half- 

 skeleton belonging to an animal, of about ten years old, received 

 from G. E. Grum-Grjimailo. The skin belonging to the skeleton 

 bears the number 3,092. 



An examination of the individual parts of the skeleton reveals 

 the following particulars. I cannot compare the dimensions of 

 the bones with those of the horse, because our horse skeletons 

 are not fully developed. 



THE VERTEBRAL COLUMN. THE FIRST CERVICAL 

 VERTEBRA (ATLAS, Figs. 11 and 12) has the form of the same 

 bone of the domestic horse. Its wings are broadened out posteriorly, 

 and the difference in their width on a level with the anterior and 



