NO. 8 UPPER EOCENE ARTIODACTYLA GAZIN 83 



Stone Springs, is much larger than L. proavus but is surprisingly simi- 

 lar. It also bears a striking resemblance to Protoceras. I believe that 

 a closer affinity is indicated here than with the camelids. L. profectus 

 may be a connecting link between the Eocene Leptotragulus and later 

 Protoceras. Possibly Cook's form Pseudoprotoceras longinaris is the 

 same as Matthew's L. profectus. As yet only the upper dentition of 

 one and the lower of the other have been described or illustrated. 



MEASUREMENTS IN MILLIMETERS OF DENTITIONS IN SPECIMENS OF 



Leptotragulus proavus 



CM. 



No. 

 IOI99 



Length of upper cheek tooth series, P'-M*, inclusive 22.0 



P', anteroposterior diameter : transverse diameter 8.0 : 6.0 



P*, anteroposterior diameter : transverse diameter 7-o : 7.3 



MS anteroposterior diameter : transverse diameter 7.4 : lo.i 



P.U. 



No. 



iisoi 



Type 



Length of lower cheek tooth series, P2-M1, inclusive 27.7 



Pa, anteroposterior diameter (at alveoli) 6.4 



P4, anteroposterior diameter : greatest transverse diameter 7-3:3-5 



Ml, anteroposterior diameter : transverse diameter of talonid 7.4: S-S 



LEPTOTRAGULUS MEDIUS « Peterson, 1919 

 Plate 17, figures 2, 3 



Type. — Rostral portion of skull with upper dentition P^-M^, CM. 

 No. 2986. 



Horizon and locality. — Uinta C, 6 miles east of Myton, Uinta Basin, 

 Utah. 



Discussion. — Peterson listed a lower-jaw portion with M3 and cer- 

 tain limb fragments as belonging to the type. However, in the lower 

 jaw the preserved tooth (probably M2 but not M3) is at the point of 

 erupting and hence does not belong to the same individual as the ros- 

 trum. For this reason there may be some doubt as to which individual 

 the limb fragments belong. 



This species is represented in the collections of the U. S. National 

 Museum by about 27 jaws and maxillae with teeth. All these are 

 from Myton pocket and all but four from the Protylopus quarry. 



The Leptotragulus medius material is a little less than four-fifths 

 the size of L. proavus. The lower premolars are relatively less slender, 

 and in P^ the parastyle, though distinct, is not so nearly conical. 



*5 Also illustrated in Peterson, 1919, pi. 27, figs- 1-4- 



