SINCLAIR: MARSUPIALIA OF THE SANTA CRUZ BEDS. 429 



molars, as well as the alveoli of the canine, the anterior premolar and the 

 first molar. 



The species may be recognized by its size, by the presence of dias- 

 temata between the premolars, by the spacing of the canine and anterior 

 premolar, and the single-rooted condition of the latter tooth. 



FIG. 8. 



Palaothentes aratce, right ramus, x -|. From an enlarged photograph of a specimen in the 

 Ameghino collection. 



The mandible, shown in the accompanying figure (text fig. 8), drawn 

 from a photograph of a jaw in the Ameghino collection, is very heavy 



and deep, with convex lower border. The horizontal ramus increases 

 slightly in depth posteriorly. 



MEASUREMENTS. 



Amegh. Coll. No. 9549. 



Length, posterior border of canine alveolus to M A , inclusive . -0235 



" of space occupied by premolars ..... .0125 



" " " " " molars .0115 



Median premolar, antero-posterior diameter .... .0025 



" " transverse " .0015 



Posterior premolar, antero-posterior "..... .006 



" " transverse " .0035 



M^, antero-posterior diameter ....... -OO35 



" transverse " -005 



Mi, antero-posterior " ...... .0025 



" transverse " .0035 



MA, antero-posterior diameter ...... .002 



" transverse " .0025 



Posterior lower premolar, antero-posterior diameter . . . -0035 

 Length of inferior molar series on alveolar border . . . .015 

 M T , antero-posterior diameter . . . .0065 



M, " "...... .004 



