TAPIRS. 369 



last also contain the remains of several forms closely allied to the 

 existing Indian species (R. Sivalensis, R. palaeindicus). 



Of the tapirs (Tapiridse) there are at present five or six recog- 

 nised species, one of which, the Malay tapir (Tapirus Malayauus}, ' 

 inhabits the Malay Peninsula and the islands of Uorneo and Suma- 

 tra, and the remainder the forest regions of South and Central 

 America, one or more of the species ascending the Andean slopes to 

 heights of from 10,000 to 12,000 feet. The Central American forms 

 (T. Bairdi, T. Dowi) have been referred by Gill to a distinct genus, 

 Elasmognathus. The genus Tapirus itself, which is not known in 

 North America previous to the Post-Pliocene period, extends back 

 in Europe to the Upper or Middle Miocene, and has continued with 

 but slight modification of form from that time up to the present 

 day. Its precursor appears to have been the Listriodon (Middle 

 Miocene), which united it with the somewhat tapiroid group of 

 the lophiodons (Lophiodontidaa — Eocene), the earliest group of 

 known perissodactyls, comprising animals ranging in size from the 

 rabbit to the ox. It is diflacult, or impossible, to determine just 

 whether the tapirs constitute a primarily Old World or New World 

 group of animals, for, despite the intimate relationship which is 

 established between them and the European Lophiodon through 

 Listriodon, an equally close connection unites them on the western 

 side of the Atlantic with genera — Helaletes (Tapirulus?), Desmato- 

 therium, and Hyrachyus— which appear to have been contempora- 

 neous with Lophiodon, and, indeed, may have preceded it. Nor 

 is it exactly impossible, as Professor Vogt has suggested, that a 

 parallel development on opposite sides of the Atlantic may have 

 evolved similar forms from slightly different ancestors. The scanty 

 remains of tapirs in the American Miocene foi-mation are referred 

 by Professor Marsh to the genus Tapiravus ; between these and 

 those of Post - Pliocene age there intervenes a complete hi- 

 atus. 



Of the horses (Equidse) there are usually recognised three groups : 

 the horses proper, the asses, and the zebras. By most zoologists 

 these are all placed in the one genus Equus, the characters defining 

 Asinus (the asses) not being considered to be of generic value. 

 Until Poliakof quite recently made known the existence of a 

 new species of horse (E. Przevalskii) from the desert wilds of Cen- 

 tral Asia it was generally supposed that the domestic animal (B. 

 35 



