NO. 8 UPPER EOCENE ARTIODACTYLA — GAZIN 85 



Discussion. — In addition to the type, there were three other lower 

 jaws and possibly a maxilla found representing this species in associa- 

 tion with the bulk of the Leptotragulus medius material in the Pro- 

 tylopus quarry. Two of the lower jaws are immature and retain milk 

 premolars along with the permanent molars. The referred maxilla 

 has but three molariform teeth preserved. 



The difference between Leptotragulus clarki and L. medius was not 

 at first evident, but when measurements were taken of a series of 

 lower dentitions, two size groups were clearly indicated. Upon more 

 detailed examination further differences observed included relatively 

 narrower teeth, particularly in the premolar region, and the fact that 

 the two crests extending posteriorly from the apex of the protoconid in 

 P3 and P4 were in consequence much less divergent than in L. medius. 

 The single upper dentition, U.S.N.M. No. 20373, preserved shows 

 that M^ to M^, if these teeth are correctly identified, though only a 

 little shorter anteroposteriorly than in L. medius, are conspicuously 

 narrower transversely. There is a possibility, however, that the first 

 of these is Dp* rather than M^, as suggested by advanced wear, in 

 which case the specimen would represent a moderately large L. medius. 

 Nevertheless, I have been unable to find evidence of a replacing P^ 

 beneath the position of the first tooth. It may be noted that Dp* in 

 Leptotragulus material would appear to be an exact replica of M^, 

 though smaller, and the wear would be relatively more advanced in 

 comparison with the tooth next posterior. 



The Leptotragulus material in the Princeton collections, found 

 associated with specimens of Pentacemylus leotensis and Protoreodon, 



MEASUREMENTS IN MILUMETERS OF DENTITION IN SPECIMENS OF 



Leptotragulus clarki 



U.S.N.M. 



No. U.S.N.M. 

 20378 No. 



Type 20380 



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

 clusive 43.0a 



Lower premolar series, Pi (at alveolus)-P4, inclusive 23.00 



Lower molar series, M1-M3, inclusive 20.3 20.1 



Pi, anteroposterior diameter (at alveolus) : greatest trans- 

 verse diameter 3.8 : 2.5 4.00 : 2.4 



Ps, anteroposterior diameter : greatest transverse diameter. . 5.2:2.3 



P4, anteroposterior diameter : greatest transverse diameter. . 5.3 : 3.4 5.4: 3.0 



Ml, anteroposterior diameter : transverse diameter of talonid . 5.6 : . . . 5.5 : 4.4 



M2, anteroposterior diameter : transverse diameter of talonid. 6.5 : . . . 6.3 : 5.1 



Ma, anteroposterior diameter : transverse diameter of trig- 



onid 9.0 : 5.0 8.7 : 5.2 



a. Approximate. 



