Peterson: Material Discovered in Uinta Basin. 97 



of the Oligocene, there are two and possibly three highly important 

 features of Leptotragulus which differ from Leptomeryx and more 

 closely suggest those of Hypertragidus, also of the Oligocene. These 

 characters are: (a) the subequal size of the incisors; {b) the larger 

 canine; (c) the reduction of the premolars to three (if that be the cor- 

 rect number in Leptotragulus). While the Uinta genus is apparently 

 related to both of these Oligocene genera it can hardly be seriously 

 considered to be a direct ancestor in either case. 



Practically equal grounds exist for considering Leptomeryx as a 

 direct descendant of Leptotragulus. In this Oligocene genus we have 

 the brachyodont dentition characteristic of Leptotragulus; molars 

 with a mesostyle, and an internal cingulum.^^ 



Taking into consideration the known characters of Leptotragulus, 

 it is perhaps most likely that the genus, if found later than the Uinta, 

 continued in the Oligocene as an independent line, which after all 

 remained rather more closely related to the true hypertragulids and 

 did not constitute a transition towards the tylopods. From what we 

 now know of Leptotragulus it is quite doubtful whether the Oligocene 

 species "Leptotragulus'' profectus Matthew^^ belongs to this genus. 

 Very recently^* Dr. Matthew has orally expressed himself as doubting 

 that "Leptotragulus" profectus from the Lower Oligocene of Montana 

 is in the line of the early camels. 



M EASUREMENTS. 



Antero-posterior diameter of upper teeth P- to and including M-. ... 35 mm. 

 Antero- posterior diameter of P- to M- 16 



" pi 6 



Transverse " " " 4-5 



"P^ 5 " 



Antero-posterior " " " 5 



"Ml 5-5 " 



Transverse " " " 7 



" M- 8 



Antero-posterior " " " 7 



" M^ 7 



Transverse " " " 9 



Diameter from alveolar border at M- to orbital border of molar 14 



Height of astragalus 15 



Breadth of astragalus, lower end 8 



^^ The cingulum of the upper molars of L. mediiis is heavier in proportion to 

 that of the specimens in the Carnegie Museum referred to Leptotragulus proavus. 

 " Bull. Amer. Mus. Nat. Hist., Vol. XIX, 1903, p. 224. 

 58 During the meeting of the Paleontological Society at Pittsburgh, Pa., 1917-18. 



7 — DEC. IS, 1919. 



