ORDER UNGULATA. 



1371 



the food of this animal mainly consisted of the leaves and twigs of juniper 

 and other coniferous plants. 



The last representative of this family is the gigantic Elasmo- 

 therium (Stereoceros) of the Pleistocene of Siberia, in which the 



dental formula of the adult is I. °, C. -, Pm. -, M. ^. The struc- 



0023 



ture of the skull and limbs is essentially Rhinocerotic ; and in the 

 former the narial septum was completely ossified, and the frontals 

 have a huge bony protuberance for the support of a large horn 

 corresponding to the second one of Rhinoceros aniiquitatis. The 

 teeth differ considerably from those of any species of Rhinoceros, 



Fig. 1246. — Right lateral aspect of the skull of a young individual of Rhinoceros ant iqui tails; 

 from the Pleistocene of Siberia. Reduced. 



and are characterised by their very tall crowns, plicated enamel, 

 and smooth plane of wear. Their structure is, however, merely an 

 extreme modification of the Rhinocerotic type, to which the nearest 

 approach among later forms is made by R. aniiquitatis. There is, 

 however, in these teeth a marked resemblance to those of Cadurco- 

 therium and Ho?nalodo?itotherium, and it is not improbable that 

 Elasmotherium presents the last representative of a stock descended 

 from the former genus which has remained altogether apart from 

 the true Rhinoceroses. 



Family Lambdotheriid^. — With the Lambdotheriidce w r e enter 

 upon the consideration of the first of three extinct families in which 

 the cheek-teeth have remarkably short (brachydont) crowns, and 

 diverge to a certain extent from the more typical Lophodont form. 

 The upper true molars (fig. 1247) may be described as consisting 

 of four columns, of which the two hindmost are frequently con- 

 nected by an oblique transvers e ridge ; while there may also be a 

 more incomplete anterior ridge. When these teeth are worn two 



