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PROCEEDINGS OF THE NATIONAL MUSEUM 



The hypocone and protostyle have a somewhat more lingual position, 

 and the lingual walls of the molars (and premolars as well) appear 

 to be more gently sloping than in Periptychus. The cusps and 

 cuspules are somewhat less widely spaced than in P. carmidens, par- 

 ticularly the protoconule and metaconule, which are located very close 

 to the protocone. 



Figure 24. — Periptychus gilmorei Gazin: Left ramus of mandible, P4-MJ (U.S.N.M. 

 No. 15689) (M3 and posterior portion of jaw fragment restored from right ramus), lateral 

 and occlusal views, X IJ^, Dragon Paleocene, Utah. 



An additional feature seen in the type of Periptychus gilmorei^ 

 but probably of no importance, as it was not observed in No. 16226, 

 is the very slight development of a "protostyle" and "hypocone" on 

 P*. This was not observed in any of the Puerco or Torre j on material. 

 Also, the third molar, on the right side only, is peculiar in that the 

 lingual wall exhibits a cuspule median to the protocone, between the 

 protostyle and hypocone. 



The lower teeth of Periptychus gilmorei, as represented by speci- 

 men No. 15689, are also nearly intermediate in most respects between 

 Carsioptychus coarctatus and Peiiptychus carinidens. The protoconid 

 of P4 is not directed posteriorly so markedly as in C. coarctatus, and a 

 small anterointernal cusp is present, this being prominent in P. carini- 

 dens but usually absent in C. coarctatus. On the posterointernal por- 

 tion of the tooth there is a small cusp; the talonid, however, is not 

 developed so much as in P. cannidens. The extent to which a meta- 



