68 Annals of the Carnegie Museum. 



may prove to be only an individual difference of the latter species. 

 The postorbital region of Merychyus arenarum Cope is proportion- 

 ately longer than in the present species. Merychyus elegans Leidy 

 and Merychyus arenarum Cope are very nearly of the same size, and 

 the other slight differences between the two species may yet prove to 

 be only individual variations. Merychyus parigonus Cope is doubt- 

 fully referred to this genus, as is also Merychyus major? 1 Merychyus 

 medius is of much larger size than the present species. Merychyus 

 harrisonensis differs from the present species by the larger size, the 

 less angulate post-temporal crest, the more outwardly directed paroc- 

 cipital process, the more depressed tympanic bulla, the more back- 

 wardly directed external auditory meatus, and the relatively smaller 

 antero-posterior diameter of M^. 



Measurements. 



mm. 



Greatest length of the skull 160 



Distance from occipital condyle to the incisors 146 



Distance from occipital condyle to M 3 65C 28 ) 



Distance from M- 3 - to the incisors 83 



Transverse diameter of occipital condyles 28 



Transverse diameter of brain case, approximately 40 



Antero-posterior diameter of the premolar series 30 



Antero-posterior diameter of the molar series 39 



Greatest length of the mandible 129 



Length of the alveolar border of mandible 83 



Vertical diameter of mandible at coronoid process 73 



Vertical diameter of mandible at anterior part of M^ 26 



Vertical diameter of mandible at anterior part of P^ 20 



Length of lower premolar series 30 



Length of lower molar series 43 



^lurocyon brevifacies gen. et sp. nov. 



(Type No. 1590, Cam. Mus. Cat. Vert. Foss. ) 



The present genus and species is based on a mutilated skull, with 

 most of the dentition of one side, the lower jaws, fragments of the 

 pelvis and a femur, three metapodials, part of the posterior dorsals, and 



27 It may become necessary to remove this species from the genus Merychyus when 

 more material is found in the locality where the type was discovered. 



28 Slight crushing of the region of the presphenoid causes this measurement to be 

 a little conjectural. 



