10 



PROCEEDINGS OF THE NATIONAL MUSEUM 



Genus PTILODUS Cope 



PTILODUS FERRONENSIS. 1 new species 



Type. — Fragment of right ramus of mandible with P4, U.S.N.M. 

 No. 16176. 



HoHzon and locality. — Dragon Paleocene, Dragon Canyon, Emery 

 County, Utah. 



SpecifiG characters. — Near Ptilodus viediaevus in size. P4 in type 

 longer, with crest less elevated posteriorly. About 12 serrations, as 

 indicated by ridges on lateral surface of tooth. Notch between an- 

 terior and posterior roots not so acute and buccal wall of crown not 

 extending down root portion so far. P^ in referred material rela- 

 tively shorter and wider and P^ slightly 

 wider than in P, mediaevus. Cusps in P^ 

 and P^ less elevated and less distinct. 

 Outer row of cusps on referred M^ less 

 developed posteriorly. 



Description. — Included in the material 

 representing Ptilodus ferronensis are five 

 lovN'er jaw fragments with P4, a maxillary 

 fragment with P^ and P^, and an incomplete, 

 isolated M^ P4 in No. 16176 (fig. 3), the 

 type of P. ferronensis.; is a little longer than 

 in Ptilodus mediaevus and has the posterior 

 portion of the crest a little less elevated. 

 The notch between the anterior and posterior 

 roots is not so acute, as viewed from the 

 outer surface, and the buccal wall of the 

 tooth does not extend so far down on the 

 roots in the type. The notch between the 

 roots of Pi in No. 16225, referred to P. ferronensis^ does not appear 

 to be so obtuse. The number of serrations on the crown of P4 in the 

 type is about 12, as indicated in part by the ridges on the lateral sur- 

 face of the tooth, apparently less by a similar method of counting 

 than in certain specimens of P. mediaevus examined, although 12 is 

 the median figure given by Simpson for the Torre j on form. 



P^ and P^ in No. 16212 compare favorably in size with Ptilodus 

 tnediaevus (Amer. Mus. Nat. Hist. Nos. 3033 and 16533), but P^ is 

 relatively shorter and wider than in the Torrejon material, and P-, 

 though incomplete posteriorly, is a little wider than in Amer. Mus. 

 Nat. Hist. No. 3033. The cusps of these two teeth in the Utah speci- 

 men are not so markedly separated and are less elevated than in 

 the Torrejon material. 



Figure 3. — Ptilodus ferro- 

 nensis, new species: Jaw 

 fragment with P4 (U.S.N. 

 M. No. 16176), type speci- 

 men, lateral and occlusal 

 views, X 3, Dragon Paleo- 

 cene, Utah. 



* Named from Ferron Canyon in Emery and Sanpete Counties, Utah. 



