36 



AMERICAN MESOZOIC MAMMALIA 



ous external cingulum and with internal cingular cusps; anterior border of orbit 

 above Mi. 



The occasional reference of this species to Triconodon has led to its being some- 

 times confused with Triconodon ferox (now Trioracodon ferox) Owen, with which it 

 has nothing to do. 



Fig. 13. Skull and jaws of Priacodon, seen from the right side. The 

 cross-lined portions are restored. The restoration is composite, al- 

 though largely based on specimens of Priacodon ferox. Inf, Infra- 

 orbital foramina; ju, Jugal; lac, lacrymal notch; the foramen is just 

 internal to this point; mas, origin for the masseter muscle; mx, 

 maxilla; pmx, premaxilla; sq, squamosal. (After Simpson, 1925B.) 



Priacodon robustus (Marsh 1879) 



1879. Tinodon robustus, Marsh, Amer. Jour. Set. (3) XVIII, 397. 

 1925. Priacodon robustus, Simpson, Amer. Jour. Sei. (5) X, 162. 



Type.— Y.P.M. No. 1 1846. Part of left lower jaw with P3 and M1-3. 



Referred Specimen. — Y.P.M. No. 10343. Part of left lower jaw with P2-3 and 

 Ml. 



Horizon and Locality. — Morrison formation. Quarry 9, Como Bluff, Wyoming. 



Di.\GNOsis. — Ms about equal to M2 and with posterior cingulum cusp small. Pi 

 shorter than P2. P2 with small anterior cusp, high central cusp, and sharp cingulum. 

 Upper teeth unknown. 



Priacodon lulli Simpson 1925 

 1925. P. lulli, Simpson, Amer. Jour. Sei. (5) X, 346. 



Type.— Y.P.M. No. 13625. Part of right maxilla, with P* and M* "^ 

 Referred Specimen. — Y.P.M. No. 10359. Part of right maxilla with M^"^. 

 Horizon and Locality. — Morrison formation, Quarry 9, Como Bluff, Wyoming. 



