508 The American Naturalist. [June, 



these differences may have been bridged over in the long period inter- 

 vening between the Wahsatch and the Miocene. We find cases of a 

 similar transformation in other lines both in the reduction of the lateral 

 toes and in th*e displacement. The characters which unite and separ- 

 ate these forms may be summed up as follows : 



Meniscotherium. Chalicotherium. 



Tridactyl (functionally) Tridactyl (structurally). 



Main axis through third digit Main axis through fourth digit. 



Sub-ungulate Unguiculate. 



Carpals and tarsals serial Carpals and tarsals displaced as in 



Perissodactyla. 



Centrale and (tibiale) Wanting. 



A fibulo-calcaneal facet None. 



Anterior portion of dental series 



reduced Same reduced or wanting. 



Superior molar buno-selenodont Superior molars buno-selenodout. 



Metaconid reduplicate Metaconid reduplicate. 



A mesostyle A mesostyle. 



Fore and Hind Feet of Chalicotherium after Gervais. 



