1887.] ^"J [Cope. 



available is the development of a naviciilocuboid bone in the posterior 

 foot. If this character be not used, then the two families will form a sin- 

 gle natural division. This definition includes in the Tragulida^ the Gelo- 

 cidfo of Schlosser, a result inevitable on any exact system. The genera 

 remaining, of which the limb structure is known, are defined as below. 

 Several other genera are known from teeth, as Micromeryx, Phanero- 

 meryx, Rutitherium, etc., but since their feet are not described, I am com- 

 pelled to omit them. 



I. Both metatarsals and metacarpals distinct ; molars brachyodout 



(Hypertragulinse). 

 «. Lateral toes behind. 

 Anterior internal crescent of inferior molars represented by a conical 



cusp LopMomeryx Pom. 



Interior crescents of inferior molars developed Dorcatherium Kaup. 



(j.a. No lateral toes behind. 

 Diastcmata in botli jaws Hypertragulus Cope. 



II. Metatarsals forming a cannon bone ; metacarpals distinct ; molars 



brachyodont (GelocinaO- 



a. Lateral digits of the manus, none of the pes. 

 Superior premolars with a small internal tubercle Leptomeryx Leidj'. 



aa. No lateral digits. 



Four lower premolars Gelocus Aym. 



Three lower premolars Bacliitherium Filhol. 



III. A metatarsal cannon bone ; metacarpals forming a cannon bone ; 



molars brachj'odont (Tragulinae). 

 a. Lateral digits well developed. 



Premolars entirely simple Tragulus Brlss. 



aa. Lateral digits weak. 

 Four inferior premolars, the posterior with branch ridges ; superior pre- 

 molar 3 with strong cingulum Ampldtragulua Pomel. 



Three inferior premolars, the posterior with branch ridges ; superior pre- 

 molar 3 with strong cingulum, e\ongn{e . ProdremotJierm^n Filhol. 



IV. Metatarsals and metacarpals unknown ; molars hypsodont 



(Hypisodontinae). 

 A diastema behind p. m. 2 ; canines not distinct Hypisodus Cope. 



Of these genera, those with the metatarsals separate, and the simplest 

 premolar teeth, must be the most primitive and nearest the Oreodontida^. 



Dorcatherium, also an existing genus, has four well-developed digits, 

 and is nearest the Oreodontida3. The only difference between that family 

 and the present one being the presence and absence of the naviculo- 

 cuboid bone respectively, Dorcatherium must be placed on the Trag- 

 ulid side of the line. Probably extinct genera will be found which 

 will connect this genus more intimately with the Oreodontida?, for 

 the slight complication of the premolars of the extinct genera of the lat- 

 ter, testify to earlier members with simpler ones. Lophiomeryx and 



