GEOLOGICAL SURVEY OF THE TERRITORIES. 595 



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Lophiodon, Cuvier. Lower jaic : Third molar with three cross-crests ; 

 premolars three, Nos. 2 aud 3 with longitudinal crests. Upper jaic ; Pre- 

 molars with longitudinal crest only, No. 1 with two transverse crests. 

 Upper jaio : Premolars with only one transverse crest. 



In Hi/rachyus the nasal bones are elongate, and unite with the maxil- 

 laries anterior to the orbit ; in E. eximius above the foramen infra-orhitale 

 exterius ; in Tapirns those bones are much shortened, and either do not 

 unite with the maxillaries or join them and the frontals above the orbit 

 at dilferent points from the anterior to the posterior borders. The tem- 

 poral fossre are so extended as to produce an elevated sagittal crest, 

 which is bifurcate behind, each projection continuing along the outer 

 margin of the occipital region as a lateral crest. The tymi)auicbone is 

 unossified beneath t\iQ meatus aiid if or ins exf emus, -which is bounded in 

 front by a strong postglenoid process. Posteriorly it is bounded by a long 

 descending mastoid process of the squamosal bone, nearly closing it 

 below. This is bounded posteriorly by a long and stout paramastoid 

 process, which is compressed from before backward and curves back- 

 ward and inward. The foramen magnum has prominent supero-lateral 

 margins which are nearly straight, aud unite at a right angle above. 



The dentition is thus: I. f ; C. ^ ; P. M. | ; M. f j a considerable dia- 

 stema separates the premolars and the canine. 



In the species studied, the vertebrie are divided as follows: C. 7 ; D. 

 18 ; L. 7 ^ S. 5 ; C. (f). Of the cervicals the seventh only is not pierced 

 by the arterial canal. The atlas has a broad flat "tranverse" process. 



The digits are 4 — 3; the third with a symmetrical hoof, those of the 

 exterior digits halved ; the former have two reverted proximal processes, 

 the latter one. The astragalus exhibits a deeplj^ grooved and extensive 

 trochlear arc, with rather long neck, which has a greater facet for the 

 astragalus, a lesser for the cuboid bone. 



From the above it is evident that this genus is nearly allied to Tapi- 

 rus and cannot be removed to another family. Professor Leidy states 

 that the i>remolars differ from those of Tapirus in having " but one in- 

 ner lobe connected with the exteral crest by two transverse crests." The 

 appearance of one lobe is jiroduced by the posterior curvature of the 

 anterior transverse crest round the inner extremity of the posterior 

 crest. 



I now proceed to describe the skeleton more exactly. 



Hyrachyus princeps. Marsh. 



Amer. Jour. Sci. aud Arts, 1872, p. 125. 



From South Bitter Creek. 



Hyrachyus exemius, Leidy. 



Hayden's Geol. Survey Montana, 1871, p. 3G1. 



Cranium. — In the specimen to be described, the anterior portion from 

 the glenoid cavities is wanting. The sagittal crest is quite elevated, and 

 the lateral occipital quite prominent, and continuous below with the 

 superior ;iiargiu of the squamosal portion of the zygoma. Four nutri- 

 tious foramina pierce the parietal bone near its middle aud above the 

 paramastoid process, and two enter the squamosal above the postglenoid 

 process. The paramastoid process approaches Tiear the occi])ital condyle 

 l3y its posterior border. I cannot discover the sutural boundaries of the 

 mastoid bone, but that separating the paramastoid process from the 

 process in front of it is distinct. The condyle of the mandible is mas- 



