526 THE MAMMALIA OF THE UINTA FORMATION. 



Specific characters. The transverse crests of the superior molars continuous; 

 the first inferior premolar rudimentary or wanting. 



Dentition. 



The superior premolar-molar series (Fig. 6 ; type of P. intermedium, Ko. 10,403), 

 consists of pm, -m.". The external crests of m.^ and m.' are wanting, as well as the 

 transverse crests of pm.'. The external crests of the two premolars are subquadrate 

 with two symmetrical vertical ridges (Fig. 6«). The anterior ti-ansverse crest of 

 pm.^ is strongly recurved, forming the single internal lobe, against which the slender 

 posterior crest abuts. The entire inner face is surrounded by a prominent cingulum. 

 The peculiarities of the molars are, the elevation of the transverse crests, the con- 

 cavity of the postei'o-external crest and faint marking of the vertical ridge. In m.- 

 and m.^ the external crest is produced widely beyond the posterior transverse crest, 

 but in m. ' the extei-nal crest is very oblique and barely overlaps the posterior trans- 

 verse crest, leaving no jDosterior fossa. These teeth closely resemble those of T. 

 cubitalis as described by Cope,* but are slightly larger. 



Meastireme?its. M. 



Svperior molars (10,403). 



Third premolar to third molar inolusive , 064 



Second molar, antero-postcrior diameter 015 



" " transverse •' Ol.j 



Fo\irlh premolar, antero-posterior diameter 01 



" transveree " 0135 



Inferior molars, etc. (10,403). 



Median incisors to third molars inclusive 102 



Length oC the premolar-molar series 076 



" " molar series 042 



" " postcanine diastema 013 



" " sym]ihysis 035 



Least width ol' " 016 



Antero-posterior diameter third superior molar 017 



Transverse " •' " " 014 



The second specimen (10,402) is the type of T. oUiquidens. It is intermediate 

 in size between JJijrac/H/us agrarius and II. nanus. There are two mandibular rami 

 (Fig. 7) with the symphysis complete and portions of the premolar-molar crowns ; also 

 a fragment of the maxilla Avith m.' and m.- and the complete crown of m.' (Fig. 10). 

 The latter tooth resembles that of the specimen- above described so closely, that it 

 enables us to identify this s])ecimen, first ascribed to Hyrachyus, as belonging to 



♦Tertiary Vcrtcbralji, p. («!. 



