56 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 128 



tive dentition of any form now included in Protoreodon. Separate 

 generic recognition was considered by Scott in 1898 but abandoned 

 the following year. I am inclined to agree that basically P. para- 

 doxicus belongs to Protoreodon, and that the differences from other 

 species are only those of degree, representing less-advanced develop- 

 ment along observed trends. It should, moreover, be noted that in the 

 illustration of the type given by both Scott (1899, pi. 4, fig. 24) and 

 Thorpe (1937, pi. i, fig. 2) the flattening of the skull is due to 

 crushing and that the unusual depth of the jaw anteriorly does not 

 take into consideration a certain amount of faulty plaster restoration. 



PROTOREODON MINOR 27 Scott, 1899 

 Plate 6, figure i 



Type. — Right and left maxillary portions with the left side ex- 

 hibiting C and P^ to M^, but M^ and M^ only partially preserved, 

 P.U. No. 1 1339. 



H orison and locality. — Uinta C, Kennedy's Hole (according to 

 Thorpe), Uinta Basin, Utah. 



Discussion. — Protoreodon minor is only a little smaller than Pro- 

 toreodon paradoxicus and on this character alone would not have been 

 separable specifically from P. paradoxicus ; however, the more-ad- 

 vanced condition of the upper premolars in P. minor, together with 

 the fact that a distinctly later horizon is represented, causes me to 

 regard P. minor as a separate species. P^ in P. minor has a distinct 

 deuterocone, and a slight basin is developed posterior to it by the 

 extension of the posterior cingulum. In P* the deuterocone has better- 

 developed crests, giving the tooth a more-selenodont appearance than 

 in P. paradoxicus. On the other hand, like P. paradoxicus, there is 

 no evidence for twinning of the primary cusp of P* in the P. minor 

 type, although in a referred specimen from the Devil's Playground a 

 slight indication of this is seen on one side only. The molars of P. 

 minor, as in P. paradoxicus, have distinctly conical paracones and 

 metacones, exhibiting likewise heavily ribbed outer walls. Also, the 

 protoconule is sharply defined. 



I have not seen lower teeth that belong without doubt to the P. 

 minor stage, as the lower teeth associated with the type specimen are 

 leptotraguline, probably Leptoreodon but not Protoreodon. Lower 

 teeth of P. paradoxicus show distinctly conical metaconids and 

 entoconids with a peculiarly prominent stylar development. Those of 

 P. minor may have been similar. 



27 Also illustrated in Scott, 1899, pl- 3. fig- 23; and Thorpe, 1937, fig. 10. 



