PREFACE. 



THE present Part of Mr. Lydekker's Catalogue completes the Order 

 UNGTJXATA, with the exception of a single group, the PROBOSCIDEA. 

 This comprises so large a series of specimens that it has been con- 

 sidered desirable to reserve it for the next Part. 



Only four species in Part III., namely Tapirus americanus, Equus 

 caballus, Rhinoceros sondiacus, Rh. unicornis, are at present existing ; 

 the remaining 78 species being all extinct. Amongst these will be 

 found many of the most ancient members of the Order, such as 

 Lophiodon, Hyracofherium, Pachynolophus, Palceofherium, Anchi- 

 lopTius, Corypkodon, Tinoceras, Dinoceras, Hyracodon, Cadurco- 

 iherium, all of which appear in the Eocene formation. 



Rhinoceros is the only genus recorded in the Catalogue which 

 has persisted on from the Eocene to the present time. 



Many ancestral forms of the Horse, Tapir, and Ehinoceros will 

 be found recorded in this Part of the Catalogue. 



HENEY WOODWAED. 



British Museum 



(Natural History), 



Department of Geology, 



April 5, 1886. 



