152 THE TRANSFORMATIONS OF THE ANIMAL WORLD 



therTcomes^the Palceotherium crassus, in which the 

 larger nasal bones no longer leave room for a trunk ; 

 afterwards comes the rhinoceros without horns, or 

 Acerotherium ; first the Acerotherium incisivum of 

 Eppelsheim, with nasal bones almost as small as in 

 the Palceotherium crassum, and then the Acerotherium 

 tetradactylum of Sansan. Horns begin to appear with 

 the rhinoceros of the sandy district of Orleans, which 

 is furnished with a very small nasal horn. In the 

 Rhinoceros Schleiermacheri of the upper Miocene the 

 bones of the nose are slightly larger than in the 

 Orleans species ; they become still thicker in the 

 Rhinoceros pachygnathus of Pikermi, already fur- 

 nished with a nasal horn and a second frontal one ; 

 in the Rhinoceros etruscus of the Pliocene the nasal 

 bones are supported from beneath by a partly ossified 

 partition ; finally, in the Rhinoceros tichorhinus of 

 the Quaternary they have become as massive as 

 possible, and are supported throughout their length 

 by a bony partition. Without even referring to 

 several anachronisms, no palaeontologist would 

 hesitate to affirm that this pedigree is incorrect in 

 almost all its parts. There exists no transitional 

 form between the Palceotherium and the group of 

 rhinoceroses, for the simple reason that the latter 

 arrived suddenly in Europe towards the commence- 

 ment of the Oligocene period, by a migration prob- 

 ably from America. On the other hand the Acero- 

 iheria are not the ancestors of the horned rhinoceros ; 

 the appearance of this last in Europe, at the com- 

 mencement of the Miocene, is likewise the result of 

 a sudden migration of Africano- Asiatic origin. 

 Lastly, even in the true rhinoceros, the above- 



