I poo.] Osborn, Phytogeny of the Rhinoceroses of Europe. 249 



difficulty in deriving the enormous frontal horn of the Pleistocene 

 species from the vigorous rudiment in A. incisivum j or the pty- 

 chodont Pleistocene molars from the simple Lower Pliocene stage. 

 There is a fine skull of A. incisivum in Halle as well as the 

 two in Darmstadt. 



7. Eastern Types. 



Incertcz Sedis. 



The Siwalik Aceratheriinse have not yet been carefully com- 

 pared by the writer. A. perimense is a very large animal from 

 Perim Island with a skull which, as restored by Lydekker ('81, 

 PI. X), suggests this phylum, although higher and shorter. 



Subfamily BRACHYPODIN^. PHYLUM III. 



Brachycephalic Rhinoceroses, short broad skulls. Teleocerine , horns when 

 developed appear on tips of nasals. Megalodine, large cutting teeth. Brachypodal, 

 short spreading feet, short limbs, body and trunk near the ground. Tridactyl, 

 probable early reduction of lateral digits. Known Geological Distribution, 

 Lozver Miocene to Lower Pliocene, inclusive, Europe and America. 



These Rhinoceroses, short and broad in all their proportions, 

 including their spreading grinding teeth, represent, so far as we 

 know, the sudden occurrence of a new type in the Lower Mio- 

 cene of Europe ; for they have no known prototypes in the Oli- 

 gocene of either Europe or America. Either the original home 

 of this type is Africa, and if so, they came into Europe with the 

 Mastodons, or they represent an offshoot of the Aceratheriinae. 

 Typical species are T. aurelianensis Nouel ; T. bracfiypus Lartet ; 

 T. gotdfussiY^ZMy^ \ T. fossiger Co'^q. Doubtful species are A. 

 persicE. and A. blanfordi. The phylum Brachypodinae takes its 

 name from one of the oldest known forms, T. brachypus Lartet, 

 although it first appears geologically in the T. auretianensis Nouel 

 of the Lower Miocene (Sables de 1' Orleanais of France), and in- 

 cludes a great variety of European and American types, extend- 

 ing to the Lower Pliocene, T. gotdfiissi Kaup. The feet in T. 

 bracJiypus and T. fossiger become extremely short. Associated 

 with the shortening of the skull is a shortening and broadening 

 of the grinding teeth — the very broad fourth upper premolar dis- 

 tinguishes the higher members of this series, notably as developed 



