28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I44 



Fragments of a pair of lower jaws (U.S.N.M. No. 22258) with 

 M2 and Ma from the lower part or Gray Bull horizon of the Knight 

 escarpment to the southwest of Elk Mountain in the Fossil Basin 

 correspond closely to the above Bitter Creek material and are also 

 tentatively referred to P. trigonodus. Possibly isolated teeth from 

 the Red Desert locality east of Steamboat Mountain represent the 

 same species. Their size is in accordance. 



PELYCODUS, near P. JARROVII (Cope) 



Four jaws and a maxilla from the slopes of Fossil Butte in the 

 Fossil Basin nearly all exhibit distinctly larger teeth than in the 

 Bitter Creek specimens. These may also represent Pelycodus 

 trigonodus but would appear to represent at least a more advanced 

 mutant. The larger of these can be closely matched in proportions 

 of teeth in Gray Bull materials tentatively identified as Pelycodus 

 jarrovii. There may be some doubt, however, as to whether P. jar- 

 rovii, originally based on New Mexican material, should be recog- 

 nized in Wyoming, but if it is, earlier P. trigonodus may be dis- 

 tinguished from it on scarcely more than an arbitrary size range, or, 

 as in the case of Bridger Notharctus tenebrosus and Notharctus 

 robustior, by an arbitrary stratigraphic limit. It may be further 

 noted that the species of Pelycodus represented in the exposures 

 around Fossil Butte exceeds in size Notharctus limosus of the La 

 Barge fauna, but not N. venticolus. 



The maxilla (U.S.N.M. No. 22259) from the saddle to the north 

 of Fossil Butte is rather close in size to the type of P. trigonodus, 

 but shows better evidence for a hypocone on the molars. In the latter 

 respect it can be closely matched in somewhat larger Bighorn Basin 

 specimens referred to P. jarrovii. It is particularly close in both size 

 and development of a hypocone crest to A.M. No. 4174 labeled 

 "small form of Pelycodus jarrovii" from an undetermined level in 

 the Bighorn Basin. 



PELYCODUS? PRAETUTUS,6 new species 

 (Plate 4, figures 2-4) 



Type. — Right ramus of mandible with P3 (incomplete) -M2, 

 U.S.N.M. No. 22262. 



Horizon and locality. — Gray Bull (Sand Coulee) equivalent of 

 Knight, i\ miles south of Bitter Creek Station, Sweetwater County, 

 Wyo. 



^ From Latin, prae, before, and Cope's species P. tutw. 



