X.I LIST OF THE FAUNA. 379 



Psittacotheriida, is represented by the genera Psittacotherium and 

 Calamodon, in which the cheek-teeth grew permanently, instead of 

 developing roots. 



The following list exhibits the chief families or minor groups 

 of characteristically North American mammals, which are either 

 entirely wanting or but sparingly represented in the Old World ; 

 those that are extinct being indicated by a t, and the absolutely 

 characteristic forms being printed in italics. 



Primates. 



t Anaptomorphidce. Anaptomorphus. 

 t Mixodectida. Mixodectes. 

 t Chriacidce. Chriads. 



Carnivora. 



Procyonidae. Represented in the Old World only by 



^Elurus. 



t Miaridce. Miacis, Didynrictis. 

 t Mesonychidcz. Mesonyx. 

 fHyaenodontidse. Patriofelis. 



Rodentia. 



Haplodon tidce. 

 Geomyidce. 



Ungulata. 



Dicotylidce. Represented by ancestral types in Tertiaries 



of E. Hemisphere. 



t Cotylopida. Cotylops, Mesoreodon, Protoreodon. 

 t Agriochceridce. Agrioch&rus. 

 t Protoceratida. Protoceras. 



Camelidae. t Pliauchenia, \Procamelus, M^eptotraguius. 



Antilocaprida. Antilocapra, t Cosoryx. 

 t Titanotheriidae. Palceosyops, Limnohyops, Telmatotherium. 

 t Uintatheriidce. Uintatherium. 



Tillodontia. 



t Psittacotheriida. Psittacotherium, Calamodon. 

 t A nchippodontidce. A nchippodus. 



