THE MIOCENE PERIOD. 



329 



the "Hollow-horned" Ruminants (Cavicornia), lastly, came 

 into existence in the Miocene period; and though the typical 

 families of the Sheep and Oxen are apparently wanting, there 

 are true Antelopes, together with forms which, if systematic- 



Fig. 244. a, Skull of Hippopotamus Sivalenis, viewed from below, one-eighth of 

 the natural size ; b, Molar tooth of the same, showing the surface of the crown, one- 

 half of the natural size ; c, Front of the lower jaw of the same, showing the six Incisors 

 and the tusk-like canines, one-eighth of the natural size. Upper Miocene, Siwalik 

 Hills. (After Falconer and Cautley.) 



ally referable to the Antilopida, nevertheless are more or less 

 clearly transitional between this and the family of the Sheep 

 and Goats. Thus the Pal&oreas of the Upper Miocene of 

 Greece may be regarded as a genuine Antelope; but the 

 Tragoceras of the same deposit is intermediate in its characters 

 between the typical Antelopes and the Goats. Perhaps the 

 most remarkable, however, of these Miocene Ruminants is the 

 Sivatheriuin giganteum (fig. 245) of the Siwalik Hills, in India. 

 In this extraordinary animal there were two pairs of horns, 

 supported by bony " horn-cores, " so that there can be no 

 hesitation in referring Sivatherium to the Cavicorn Rumin- 

 ants. If all these horns had been simple, there would have 



