2V0.1.] COPE ON MIOCENE FAUN.E OF OREGON. 69 



molar. In P. heterodontus it issues above the anterior part of the first 

 true molar. A sharj) angle sei^arates the exterior and extero-inferior 

 faces of the malar bone. 



Measurements. 



M. 



Leugtli of dental series from base of first incisor 0.257 



Length, of incisors on cliorcl 0.023 



Space between tbird incisor and canine 0.006 



Lengtb of crown of tbird incisor 0.013 



Antero-posterior diameter of tbird incisor 0.008 



Lengtb of interval between canine and first premolar 0.011 



Lengtb of interval between first j)remolar and second isremolar 0.020 



Lengtb of tbree contiguous premolars 0.035 



Lengtb of tbii'd premolar 0.014 



Widtb of tbird premolar (greatest) 0.0075 



Lengtb of true molar series 0.057 



^. ^ „ ^^ . , (antero-posterior 0.018 



Diameter of second true molar < , r> r,,-, 



( transverse 0.018 



_. , « ^1 . T . , (antero-posterior 0.022 



Diameter of tbird true molar < , ^ ,^ r.,r. 



( transverse 0.019 



Discovered by 0. H. Sternberg in the Loup Fork beds of Cottonwood 

 Creek, Oregon. 



