Peterson: A New Titanothere from the Uinta Eocene. 37 



No. 2859, 

 Mm. 

 Length of inferior molar-premolar series 255 



Length of inferior premolar Fcries 94 



Length of inferior molar series 160 



Py. Antero-posterior diameter 14 



Pj-, Transverse diameter 10 



Pj. Antero-posterior diameter 24 



Pj. Transverse diameter 14 



P3. Antero-posterior diameter 28 



Pj. Transverse diameter 18 



Pj. Antero-posterior diameter 29 



P J. Transverse diameter 20 



My. Antero-posterior diameter 38 



Mx- Transverse diameter 26 



M5. Antero-posterior diameter 49 



Mt. Transverse diameter 30 



Mj. Antero-posterior diameter 78 



M3. Transverse diameter 32 



Vertebral Column. 

 The atlas of the type (No. 2859) is quite complete. There is 

 also the greater portion of an atlas with the paratype No. 2860. 



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Fig. 2. Diploceras osborni Peterson. (Type. No. 2859 ) X 3. Anterior 

 view of atlas. 



With regard to the posterior division of the arterial canal it may be 

 said that there appears to be some variation in the Uinta species. 

 Thus it is seen that in the type the base of the transverse process is 

 pierced by a small foramen, see Fig. 3, while in the paratype there 

 is no evidence of this foramen on the posterior face of the transverse 

 process. Of the later Uinta forms there is apparently no atlas known. 

 In comparing the Oligocene Titanotheres, with the Uinta specimens 

 before us, there is a corresponding variation. The atlas of the Oligo- 

 cene types further varies in the antero-posterior diameter, and in the 

 prominence of the neuial spine and the transverse processes. 



