1881.J 



379 



[Cope. 



The genera included in these families are the following. The table 

 shows their geological distribution : 



LopJiiodontidcR. 



Hyracotherium Ow. . . 



Pliolophus Ow 



? Lophiotherium Gerv. 

 Pachynolophus Pom. . 



Helaletes Marsh 



Lophiodon Cuv 



Hyrachyus Leidy 



Colonoceras Marsh 



Triplopidm. 

 Triplopus Cope 



HyracodontidcB. 

 Hyracodon Leidy 



BMnocerontidce. 



Aceratherium Kaup. . . 



Ccenopus Cope 



Diceratherium Marsh . 



Zalabis Cope 



Aphelops Cope 



Ceratorhinus Gray.. . . 

 Rhinocerus Linn. . . . . , 



Peraceras Cope 



Atelodus Pom 



Coelodonta Broun 



Tapiridm. 



Listriodon Gerv. . . . 



Tapirus Linn 



Elasmognathus Gill. 



ChalicotTieriidm. 



EOCENE. 



MIOCENE. 



Lower Upper Lower Middle Upper 



12 



4 



Rhagatherium Pict 



Leurocephalus S. S. and O 



Palseosyops Leidy 



Limnohyus Leidy 



Lambdotherium Cope 2 



Propalseotherium Gerv 1 



Chalicotherium Kaup 



Nestoritherium Kaup 



Meniscotherium Cope 



MacraucTieniidoR. 

 Macrauchenia Ow 



PROC. AMER. PHILOS. SCO. XIX. 108. 2V. 



2 



1 



3 



3 



11 



?3 



?1 



t 3 



PRINTED MAY 14, 1881. 



