COPE ON NEW EXTINCT VERTEBRATA. 381 



an animal of the size of the Oreodon major. It has been somewhat flat- 

 tened by lateral pressure, but is seriously injured in the nasal region 

 only. 



The front is convex and descending toward the muzzle, and the sa. 

 gittal crest is strong. The orbits were probably closed behind, but the 

 postorbital border was narrow, and is not completed next the frontal in 

 the specimen, which is probably due to pressure. The lateral spines of 

 the premaxillary bones rise obliquely backward, shortening the face 

 so as to indicate that the nasal bones are short. The naso-maxillary 

 suture is short, and is terminated behind by a very large facial foramen, 

 which has a greater vertical than longitudinal extent. It bounds the 

 anterior margin of the thin lachrymal bone at the fundus of the pre- 

 orbital fossa. The facial plate of the maxillary is plane. The zygo- 

 matic arc hsprings abruptly outward above the fourth premolar, and 

 has a wide lateral curvature round the zygomatic fossa. Its horizontal 

 width equals its depth at the last molar tooth. The squamosal portion 

 of the zygomatic arch is expanded horizontally, and not vertically, hav- 

 ing a nearly straight lateral border to behind the line of the postglenoid 

 process, where it terminates in an obliquely truncate extremity. This 

 truncation forms with the mastoid region a deep notch. The post- 

 glenoid process is small, and is confined to the inner half of the zygo- 

 matic portion of the squamosal bone. The orbit is rather small. The 

 infraorbital foramen is small, and probably issues above the fourth pre- 

 molar, but its position is somewhat obscured in the specimen by fissures. 

 The nasal fissure of the premaxillary extends downward nearly to the 

 line of the alveolar border of the maxillary. The alveolar border of 

 the premaxillary extends below this line, and is convex downward. 



The mandibular ramus projects a little behind the condyle, and de- 

 scends in a vertical straight line, and is then regularly convex. The 

 symphysis is quite oblique. 



The second and third premolars of the superior series are longer than 



the fourth, and their external apices are in advance of the middle. The 



superior true molars are remarkable for the great prominence of the 



vertical ribs which mark the anterior horns of the external crescents. 



The posterior one, at the middle of the tooth, is the most prominent, and 



encloses with the external face of the crown a deep fossa. There is a 



third or posterior column on the last superior molar, which forms a small 



heel on section. The external ribs of the inferior true molars are very 



prominent, and the last possesses a prominent fifth lobe, or heel. The 



incisors are rather small, the external as usual the largest. The canines 



are but little enlarged. 



Measurements. 



M. 



Length from premaxillary to occipital condyles 0.225 



Lengtli from premaxillary to postglenoid process -. 0.175 



Length from premaxillary to end of last upper molar 0.116 



Length from premaxillary to opposite anterior border of orbit 0.084 



Width of zygoma external to postglenoid process 0.027 



