34 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 128 



above Ouray. Although there were three specimens from this quarry- 

 tentatively referred to Pentacemyliis progressus, all those referred to 

 P. leotensis are characterized by generally smaller and narrower mo- 

 lars. The premolar series may be about as long as in P. progressus, 

 but these teeth are significantly smaller and separated from one an- 

 other anteriorly by more noticeable diastemata. P4 is decidedly small 

 in P. loetensis. 



An interesting comparison may be made of the artiodactyl elements 

 in the two above-mentioned quarries. The Leota Ranch quarry, 

 which Dr. John Clark informs me is stratigraphically higher in the 



MEASUREMENTS IN MILLIMETERS OF DENTITIONS IN SPECIMENS OF 



Pentacemylus leotensis 



P.U. 



No. P.U. 



16310 No. 



Type 16351 



Length of upper cheek tooth series, C (at alveolus )-M^ 



inclusive 43.00 43.8 



Length of upper cheek tooth series, P*-M^ inclusive 37.0 38.5 



Upper premolar series, P*-P*, inclusive 20.5 21.8 



Upper molar series, M*-M^ inclusive 16.8 17.0a 



C, anteroposterior diameter (at margin of enamel) : great- 

 est transverse diameter 3.0 : 2.1 



P\ anteroposterior diameter: greatest transverse diameter. . 4.0: 1.8 4.1 : 1.4 



P', anteroposterior diameter : greatest transverse diameter. . 4.9: 2.3 4.5 : 1.9 



P^ anteroposterior diameter : transverse diameter* 5.4 : 4.0 5.5 : 4.2 



P*, anteroposterior diameter : transverse diameter 4.0 : 5.4 4.2 : 5.5 



M\ anteroposterior diameter : transverse diameter* 5.4 : 6.9 5-3 : . . . 



M^ anteroposterior diameter : transverse diameter 5.8 : . . . 6.0:7.7 



M', anteroposterior diameter : transverse diameter 6.0 : 7.2a 



Length of lower cheek tooth series, C (at alveolus) -Ma, 



inclusive 48-5 43-5 



Length of lower cheek tooth series. Pi (at alveolus) -M3, 



inclusive 44-8 39.3 



Lower premolar series, Pi (at alveolus) -P4, inclusive 24.2 21.2 



Lower molar series, M1-M3, inclusive 20.7 18.3 



C, anteroposterior diameter (at margin of enamel) : great- 

 est transverse diameter 2.2a : . . . 2.7 : 1.6 



Pi, anteroposterior diameter : greatest transverse diameter. . 3.0: 1.8 



Pj, anteroposterior diameter : greatest transverse diameter. . 5.0a ■.1.7a 



Pa, anteroposterior diameter : greatest transverse diameter : 2.3 5.4: 2.0 



P4, anteroposterior diameter : greatest transverse diameter. . 5.90: 3.1 5.4 : 2.9 



Ml, anteroposterior diameter : transverse diameter of talonid. 6.00 : 3.7 5.3 : S-^a 



M2, anteroposterior diameter : transverse diameter of talonid. 6.3 : 4.3 5.7 : 4.6 



Ma, anteroposterior diameter : transverse diameter of trigonid 8.2 : 4.0 7.7 : 4.3 



a, Approximate. 



• Measurements of posterior upper premolars are taken anteroposteriorly across outer por- 

 tion and transversely perpendicular to outer margin. Those of upper molars are taken 

 anteroposteriorly perpendicular to anterior margin and transversely across anterior portion 

 of tooth. 



