SINCLAIR: MARSUPIALIA OF THE SANTA CRUZ BEDS. 357 



the lambdoidal crest expanded as a broad semicircular frill. The infra- 

 orbital canal is double, neither branch being as large as the single canal 

 in B. excavata. If constant, this may prove to be a good specific char- 

 acter. The skull is a fourth larger than in B. excavata. 



It is not yet possible to separate generic from specific characters in the 

 skeleton, as B. tuberata is the only species in which the skeleton is at all 

 well known. Its important features have already been noted in the de- 

 scription of the genus. 



MEASUREMENTS. 



Skull, length, prcmaxillae to lambdoidal crest ...... .230 



" width across jugal arches ........ .160 



" " between orbits ......... .062 



Face, length to anterior orbital border ....... .076 



Cranium, length to anterior orbital border . ...... .141 



" least width of brain case . . . . . . ... .027 



Palate, length from alveolus of median incisor to palato-nanal border . . . 104 

 " width between canines . . . . . . . . . .0245 



" " " posterior premolars . . . . . . . .037 



" " "Mi 075 



Mandible, length . . 186 



" transverse diameter of condyle ....... .0423 



" length of symphysis ........ .060 



" depth below posterior premolar . . . . . . . .031 



" " " M T 038 



Superior dentition, length, median incisor to MA. . . . . . .113 



" " " of premolar series ...... -0333 



" " " " molar " 045 



Inferior dentition, length, base of median incisor to M ? . . . .1025 



" " " of premolar series ...... .035 



" molar " 0515 



Median upper incisor, width of crown ...... .002 



Lateral " " .0036 



Alveolus of upper canine, length ....... .0165 



" " " " width .0135 



Anterior superior premolar, antero-posterior diameter. . . . -0075 



" transverse "... .0047 



Median " " antero-posterior "... .010 



transverse " . . .0063 



Posterior " " antero-posterior "... -0145 



" " " transverse .009 



Mi, antero-posterior diameter .... -O 12 



" transverse "... -0082 



M, antero-posterior " -0126 



" transverse " . 9S 



