NO. 8 UPPER EOCENE ARTIODACTYLA — GAZIN 57 



It is entirely possible that P. minor is no more than a variant in time 

 of P. paradoxicus and that P. minor in turn gave rise to the form de- 

 scribed as a new species, Protoreodon petersoni, in the M)rton pocket 

 and Leland Bench draw collections. 



MEASUREMENTS IN MILLIMETERS OF DENTITIONS IN SPECIMENS OF 



Protoreodon minor 



P.U. 



No. U.S.N.M. 

 11339 No. 

 Type 20674 

 Length of upper cheek tooth series, C-M^ inclusive, meas- 

 ured at alveoli 55.0 



Length of upper cheek tooth series, P^-M', inclusive, meas- 

 ured at alveoli 46.9 



Upper premolar series, P^ (at alveolus)-P^ inclusive 25.2 



Upper molar series, M'-M", inclusive, measured at alveoli. . 22.0 22.0a 

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

 verse diameter 5.5 : 4.8 



P^ anteroposterior diameter : greatest transverse diameter. 6.0 : 3.8 



P^ anteroposterior diameter : transverse diameter* 6.5 : 6.0a 6.4 : 6.5 



P^ anteroposterior diameter : transverse diameter 6.0 : 7.5 6.0 : 7.3 



M*, anteroposterior diameter : transverse diameter* 7.2 : 8.8 



M^ anteroposterior diameter : transverse diameter 8.1 : 11. 7 8.2 : 10.4 



M^ anteroposterior diameter : transverse diameter 8.0a : 12.0 8.5 : 11.6 



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 taJcen 

 anteroposteriorly perpendicular to anterior margin and transversely across anterior portion 

 of tooth. 



PROTOREODON PRIMUS 28 (Peterson), 1934 



Type. — Portion of skull and jaws, CM. No. 11893. 



Horizon and locality. — Randlett member of Duchesne River forma- 

 tion, Randlett Point, Uinta County, Utah. 



Discussion. — The specimen that Peterson designated as the type 

 of Mesagriochoerus primus from Randlett horizon and that (CM. 

 No. 1 1904) from the Halfway, which he regarded as the paratype, 

 appear to represent a distinct species. The slenderness of the pre- 

 molars noted by Peterson is distinctive. Most of the characters, how- 

 ever, that he cited as indicating a separate genus, and certainly 

 those in particular that he regarded as more closely foreshadowing 

 Agriochoerus, are not significant in comparison with material of 

 Protoreodon pumilus annectens from Myton pocket. The twinning of 

 the primary cusp in P* is no further advanced than in much of the 

 Myton material, and the crescentic deuterocone is somewhat more 

 like that noted in Protoreodon petersoni than in Agriochoerus, as for 



28 Illustrated in Peterson, 1934, figs. 3-5. 



