26 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I44 



PALAEOSINOPA, sp. 



Several isolated teeth of Palaeosinopa from the Bitter Creek lo- 

 cality in both the National Museum and Marsh collection indicate 

 a species decidedly smaller than Gray Bull P. veterrima. They are 

 only a little smaller than in P. didelphoides, but the type of Cope's 

 species is from the Lost Cabin beds, so that there may be some doubt 

 as to its presence in the lowest horizon of the Knight. The isolated 

 upper molars from Bitter Creek are relatively much narrower than 

 in P. veterrima and show much less development of the cingulum. 

 Two lower premolars, Y.P.M, No. 14700, are a little shorter than in 

 P. veterrima and much more slender. Matthew cites narrower lower 

 molars for P. didelphoides but the dimensions he gives for M2 (1918, 

 p. 590) would indicate that this tooth is relatively wider than in 

 P. veterrima. The Bitter Creek teeth may well represent a distinct 

 species but the materials known are clearly inadequate for diagnosis 

 under the circumstances. 



APATEMYIDAE 



APATEMYS HtJRZELERI,* new species 



(Plate 2, figure 7) 



Type. — Right ramus of mandible with I, M2, and the talonid 

 portion of Mi, U.S.N.M. No. 22386. 



Horizon and locality. — La Barge faunal horizon (Lost Cabin 

 equivalent), 12 miles north of Big Piney, Sublette County, Wyo. 



Specific characters. — Size appreciably larger than Gray Bull Teil- 

 hardella chardini Jepsen, close to Bridger Apatcmys belhdus Marsh, 

 but molars distinctly narrower. 



Description. — Only the type lower jaw of Apatemys hilrzeleri is 

 known. Much of the bone is missing but the incisor is complete. 

 Also the second molar and the posterior portion of the first are pre- 

 served. I am in agreement with McKenna that this form should be 

 referred to Apatemys rather than Teilhardella. 



The large lower incisor is decidedly procumbent. Its crown por- 

 tion shows enamel on the outer surface and on the lower or anterior 

 part of the medial side. Along the outer margin of the concave upper 

 surface of the tooth crown the upper margin of the outer enamel 

 shows slight or subdued serration. The dorsoventral and transverse 

 diameters of this tooth just posterior to the crown, about where the 

 tooth would emerge from the alveolus, are 2.5 and 1.4 mm. respec- 



* Named for Dr. Johannes Hiirzeler in recognition of his work on apatemyids. 



