PALEOCENE jMAMMALS OF CENTRAL VTAH GAZIN 



23 



have a weaker, less inflated appearance. The posterior portion of 

 the external cingulum of M\ Nos. 16178 (fig. 13) and 15783, rises 

 forward on the protocone much as in the Torrejon material of 

 Tricentes, but the inner cingulum does not extend ai'ound the pro- 

 tocone as is common, though not invari- 

 able, in Tincentes suMrigonus. In 1M-, 

 Xo. 16179 (fig. 13), the cingulum appears 

 to be continuous around the protocone. 

 The enamel is weakly rugose on both M^ 

 and M^, but there is no indication of a 

 mesostyle on the cingulum or between the 

 paracone and metacone on these teeth. 



A maxillary portion with M^ and an in- 

 complete M-, Xo. 16206, may represent 

 Tncentes elassus. The teeth are a little 

 smaller than in T. subtrigonus but other- 

 wise show no importance differences. The enamel is somewhat more 

 smooth than in the type but the teeth are well worn. The inner por- 

 tion of M- shows a slightly heavier cingulum around the protocone 

 than in the isolated M- described above. 



The lower molar, No. 16215, in the collection shows no important 

 differences from material of Tricentes subtrigonus except that the 

 paraconid is perhaps a little more lingual in position. 



The anteroposterior and transverse diameters of the type, M^, 

 are 5.1 and 5.6 mm., respectively. 



Figure 13. — Tricentes elassus, 

 new species: XP (U.S.N.M. 

 No. 16178), type specimen (on 

 right), andM? (U.S.N.M. No. 

 16179), occlusal views, X 3, 

 Dragon Paleocene, Utah. 



Genus GONIACODON Cope 



GONIACODON? species 



An upper molar, U.S.N.M. No. 16207, closely resembles M^ in 

 Goniacodon levisa7ius, equaling in size this tooth in individuals hav- 

 ing somewhat smaller teeth than the average in the known material. 

 The only apparent distinction lies in the extension of the cingulum 

 on the anterior wall of the tooth to a more lingual point than in 

 Goniacodon levisanu^. The anteroexternai and posteroexternal styles 

 are broken off so that the direction or extent of these angles cannot 

 be determined. The tooth is ]iot greatly different from M- in Glaeno- 

 don prooyonoides^ but the resemblance between the Utah specimen 

 and M^ in G. Jevisanus is more striking. 



An isolated upper premolar. No. 16208, resembles P- in Goniacodon 

 levisanus so closely that it may well belong to the same form as 

 that represented by the molar. The principal cusp is broken down, 

 but the deuteroconid i)ortion is preserA ed and corresponds closely to 

 that in G. Uvisajvus, except in being a little more restricted antero- 

 posteriorly. The outer portion of the tooth is somewhat distorted, 



