THE MIOCENE PERIOD. 317 



as has been previously mentioned, differed from that of the 

 Horse in the fact that whilst both possess the middle toe greatly 

 developed and enclosed in a broad hoof, the former, in addition, 

 possessed two lateral toes, which were sufficiently developed 

 to carry hoofs, but were so far rudimentary that they hung idly 

 by the side of the central toe without touching the ground 

 (see fig. 230). In the Horse, on the other hand, these lateral 

 toes, though present, are not only functionally useless, but are 

 concealed beneath the skin. Remains of the Hippai'ion have 

 been found in various regions in Europe and in India ; and 

 from the immense quantities of their bones found in certain 

 localities, it may be safely inferred that these Middle Tertiary 

 ancestors of the Horses lived, like their modern representa- 

 tives, in great herds, and in open grassy plains or prairies. 



Amongst the Even-toed or Artiodactyle Ungulates, we for 

 the first time meet with examples of the Hippopotamus, with its 

 four-toed feet, its massive body, and huge tusk-like lower 

 canine teeth. The Miocene deposits of Europe have not 

 hitherto yielded any remains of Hippopotamus ; but several 

 species have been detected in the Upper Miocene of the Siwalik 

 Hills by Dr Falconer and Sir Proby Cautley. These ancient 

 Indian forms, however, differ from the existing Hippopotamus 

 amphibius of Africa in the fact that they possessed six incisor 

 teeth in each jaw (fig. 244), whereas the latter has only four. 



Amongst the other Even-toed Ungulates, the family of the 

 Pigs (Suida) is represented by true Swine (Sus Erymanthius), 

 Peccaries {Dicotyks antiqujis), and by forms which, like the 

 great Elotheriiim of the American Miocene, have no represen- 

 tative at the present day. The Upper Miocene of India has 

 yielded examples of the Camels. Small Musk-deer {Amphi- 

 tragulus and Dremotherium) are known to have existed in 

 France and Greece ; and the true Deer ( Cervidce), with their 

 solid bony antlers, appear for the first time here in the person of 

 species allied to the living Stags [Cervus), accompanied by the 

 extinct genus I)orcatheriu?n. The Giraffes {Ca??ieiopardaHdcB), 

 now confined to Africa, are known to have lived in India and 

 Greece ; and the allied Helladotherium, in some repects inter- 

 mediate between the Giraffes and the Antelopes, ranged over 

 Southern Europe from Attica to France. The great group of 

 the "Hollow-horned" Ruminants {Cavicomia), 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 systemati- 

 cally referable to the Antilopidce, nevertheless are more or less 

 clearly transitional between this and the family of the Sheep 



