PALEOCENE MAMMALS OF CENTRAL UTAH GAZIN 



11 



An incomplete M^ in the collection, No. 16216, shows the outer row 

 of cusps less developed posteriorly than in Amer. Mus. Nat. Hist. 

 No. 3033 from the Torrejon. 



The length of P4 in the type, No. 16176, of PtU-odus ferronensis 

 is 9 mm. In No. 16212 P^ is 3.3 mm. long and 2.8 wide, and P- is 

 3.5 mm. wide. 



INSECTIVOFvA 



Genus APHRONORUS Simpson 



APHRONORUS SIMPSONI^ Gazin 

 Aphronorus simpsoni Gazin, 1938, p. 273. 



About 19 specimens, consisting of isolated teeth or jaw fragments 

 with one to four teeth, from the Dragon level are considered to 

 represent Apkrono7ii^. All but 

 three of these, upper premolars, 

 are lower jaw remains. The up- 

 per molar earlier (Gazin, 1939b, 

 p. 275) thought to be of Aphro- 

 norus simpsoni is now cited here- 

 in as pantolestid (b). 



Aphronorus simpsoni is close 

 in size to A. fmudator from the 

 Crazy Mountain Fort Union but 

 differs from this species in cer- 

 tain relative proportions, which 

 are outside the limits given by 

 Simpson for the middle Paleo- 

 cene form. The ramus. No. 15539 

 (fig. 4), made the type, is slight- 

 ly deeper than in the several 

 Fort Union specimens that the 



writer examined, a difference more noticeable in the posterior 

 portion. Also, the posterior molars are relatively larger, par- 

 ticularly M3, which is larger than in any of the Fort Union 

 specimens examined. However, the teeth are relatively slender. 

 This is most noticeable in P4, wliich combines the greatest length 

 with the least width given by Simpson for A. jraudator. Moreover, 

 the posterior wall or shear of the ti-igonid in the molars is not so 

 distinctly transverse, but directed slightly more forward externally. 

 In P4 the shear is more nearly transverse though somewhat irregular 

 as a slight ridge extends down the posterior wall of the metaconid 

 and unites with the hypoconid crest. 



Figure 4. — Aphronorus simpsoni Gazin: 

 Left ramus of mandible with P^-Ms (U. 

 S.N.M. No. 15539), type specimen, later- 

 al and occlusal views, X 4, Dragon Pa- 

 leocene, Utah. 



2 Named for Dr. G. G. Simpson. 



