NO, 8 UPPER EOCENE ARTIODACTYLA — GAZIN 59 



The rather interesting collection of artiodactyl remains obtained by 

 Princeton at the Leota Ranch quarry includes several protoreodont 

 specimens. These are of a form about as large as P. p. annectens, but 

 the teeth, particularly those of the lower series, are distinctly narrower 

 than in the Myton pocket series and are hence tentatively referred 

 to Protoreodon primus. As previously noted, the Leota Ranch quarry 

 horizon is regarded as later than that at Myton pocket, but earlier 

 thaij Randlett. 



PROTOREODON PETERSONI.^^ new species 

 Plate 7 



Type. — Skull and jaws with complete dentition, and other skeletal 

 portions, P.U. No. 14404. 



Horizon and locality. — Uinta C, Myton pocket, Uinta Basin, Utah. 



Specific characters. — A little smaller than Protoreodon minor but 

 decidedly more progressive in the achievement of a selenodont denti- 

 tion. P^ and P^ both with deuterocone posterior in position and with 

 a small posterointernal basin. P* has a single primary cusp and 

 highly selenodont deuterocone. The outer cusps of upper molars are 

 more crescentic than in P. minor, having their outer walls smoothly 

 concave with the ribs weak or indistinct. Parastyle of each is perhaps 

 less outstanding laterally, mesostyle compressed, and the lateral cingu- 

 liun less shelflike. Protoconule is weak on M^, weak or absent on 

 M^, and usually absent on M^. On some upper molars there is a spur 

 extending anteriorly from about midway along anterior crest of the 

 metaconule which may, particularly on M^, join the posterior crest 

 of the protocone. P4 is much as in Protoreodon pumilus but in one 

 specimen exhibits a small spur extending anterolingually into the 

 talonid basin from about midway across the posterior wall. Inner 

 cusps of the lower molars are less conical than in P. paradoxicus, with 

 the outer walls more flattened and the stylids somewhat less pocketed 

 or shelf like than in the larger protoreodonts. 



Discussion. — In addition to the type there are three skulls, two 

 of which are immature but remarkably complete with jaws and other 

 skeletal portions, in the Princeton collections, Nos. 14401, 14402, and 

 14403, and four partial dentitions in the collections of the U. S. Na- 

 tional Museum. All but one of the specimens are from Myton pocket. 

 One of these, U.S.N.M. No. 20386, including the right maxilla and 

 portions of both lower jaws, is from Leland Bench draw. In all in- 

 stances the material is clearly separable from the P. minor material 



29 Named for O. A. Peterson. Illustrated also in Scott, 1937, fig. 232. 



