MAMMALIA. 



21 



of southern Europe, is also represented by jaws and teeth Pier-oases 

 in the Norfolk Forest Bed, from which Mr. Savin collected 7 ' 8- 

 the series of specimens in Pier-case 7. True two-horned 

 rhinoceroses are found in the Lower Pliocene of Eppelsheim 

 (Hesse-Darmstadt), Pikermi (Greece), the Isle of Samos, and 

 Maragha (Persia), as shown by fine specimens in Pier-case 8. 

 Pliocene rhinoceroses are likewise found in the Siwalik 

 Formation of India, and here there are not only two-horned 

 species but also direct ancestors of the one-horned species 

 (B. unicornis) which now lives in India. Their remains were 

 collected chiefly by Falconer and Cautley and are exhibited 

 in Pier-case 7. 



Pig. 11. — Skull and lower law of a Hornless Rhinoceros (Aceratherium 

 megalodus), from the Upper Miocene of Colorado, U.S.A. ; one-sixth 

 nat. size. (After B. D. Cope.) 



In the Miocene and Oligocene formations both of Europe pier-case 8. 

 and North America, and in the Lower Pliocene of Europe and 

 Asia, there is evidence of numerous ancestral rhinoceroses, 

 most of which were almost or quite hornless (e.g., Acera- 

 therium). In fact, the American representatives of the 

 Ehinoceridae (Fig. 11) seem to have become extinct at the 

 end of the Miocene period before they had acquired more 

 than the slightest trace of a horn. As in the true modern 

 rhinoceroses, of course, this structure is never fossilised — its 

 presence or absence is merely inferred from the size of the 

 nasal bones and from the presence or absence of a roughness 



