NO. I LOWER EOCENE MAMMALIAN FAUNAS — GAZIN 2$ 



and the talonid portion is much more elongate as in Palaeosinopa 

 and Pantolestes. 



MEASUKEMENTS IN MILLIMETERS OF POSTERIOR LOWER MOLARS 



IN SPECIES OF Palaeosinopa and Amaramnis 



M2, anteroposterior diameter: transverse diameter 



Ms, anteroposterior diameter : transverse diameter 



* Approximate. 



PALAEOSINOPA, cf. DIDELPHOIDES (Cope) 



The lower cheek teeth of the right side, including P2-M3 (U.S.N.M. 

 No. 22453), associated with fragments of the jaw, undoubtedly of 

 Palaeosinopa, were found in the New Fork tongue. The lower 

 molars, the first two of which are badly worn so that their length may 

 be slightly less than normal, measure 15 mm. This is very near the 

 measurement of 15.5 mm. given by Matthew (1918) for a specimen 

 of Palaeosinopa didelphoides. 



Comparison of the New Fork specimen with Bridger Pantolestes 

 longicaiidus shows the two to be rather close. The premolars are a 

 little longer and more slender, and on Mg, which is the least worn 

 molar, the paraconid is higher and more lingual in position than in 

 the Bridger specimens observed. 



A single lower molar (U.S.N.M. No. 22251), possibly M2, from 

 the Cathedral Bluffs tongue on the east side of the Washakie Basin 

 is referred tentatively to Cope's Lost Cabin species. It is about the 

 size of M2 in the New Fork specimen and has the dimensions given 

 by Matthew (1918, table, p. 590) for this tooth in P. didelphoides. 

 It resembles in detail M2 in the specimen that he figured (1918, 

 fig. 16). Nevertheless, it should be noted that with this very limited 

 material there is little that can be observed to distinguish the Ca- 

 thedral Bluffs form from Bridger Pantolestes longicaudus. 



MEASUREMENTS IN MILLIMETERS OF TEETH IN LOST CABIN 



AND NEW FORK SPECIMENS OF Palacosinopa 



P. didel- 

 phoides P., cf. dideU 

 A.M. phoides 



Pa, anteroposterior diameter : transverse diameter. . 

 P4, anteroposterior diameter : transverse diameter.. 

 Ml, anteroposterior diameter : transverse diameter.. 

 M3, anteroposterior diameter : transverse diameter.. 

 Ms, anteroposterior diameter : transverse diameter.. 



No. U.S.N.M. 



4804 No. 



Type 22453 



S.o : 2.1 



5.4:2.5 



5.2:3.4 5-o:3-S 



5-5 : 3.9 S.I : 4-0 



6.3:3-6 5.5:3.2 



