154 



University of California Publications. 



[Geology 



responds to a transverse ridge on the crown. The anterior wall 

 of the alveolus is plane, while the posterior is slightly convex, 

 with indications of a convex median rib. 



The alveolus for the third molar is almost quadrangular in 

 outline. The anterior wall is slightly concave, while the pos- 

 terior is convex with a stronger convex rib situated about mid- 

 way. The lateral walls meet the anterior face at a right angle. 

 They are both grooved. A third lower molar of the left side. 

 No. 8704 is represented on Plate 23, figures 4 and 4a. 



The fourth molar alveolus is cordate in cross-section, with 

 the indentation on the outer side. The anterior lobe produced 

 by this groove projects beyond the posterior. The tooth is rep- 

 resented in the cave collection by three specimens, Nos. 8485, 

 8328 and 8339, but none of them have the triturating surfaces 

 preserved. 



Fourteen molars referable to this species were collected from 

 the cave, principally from stratum E. Three were found in 

 stratum A and several in the Buried Gallery from stratum E or 

 F. Some of these are shown on Plate 23, figures 3-5<x and 8. Sev- 

 eral are considerably curved and are doubtless of the superior 

 series. They correspond in size to the lower molar alveoli. The 

 last superior molar of the left side, No. 8497 is represented on 

 Plate 23, figure 8. It is a triangular tooth with the posterior 

 side plane, the anterior convex, and the outer plane and meet- 

 ing the posterior at a right angle. The triturating surface of 

 the crown has been injured by rodents. 



Measurements. 



Length of inferior molar series measured on alveolar border. . 53.5mm 



Greatest antero-posterior diameter of the alveolus of JVL 15 



Greatest transverse diameter of the alveolus of M 2 17 



Greatest antero-posterior diameter of the alveolus of M 3 15 



Greatest transverse diameter of the alveolus of M 3 17 



Greatest antero-posterior diameter of the alveolus of M 4 16 



Greatest transverse diameter of the alveolus of M 4 17 



Depth of ramus below alveolar border of Mj 50 



Least distance between alveolar border behind M 4 and inferior 



border of jaw 43.5 



Superior molar No. 8702, antero-posterior diameter at triturat- 

 ing surface 12 



Superior molar No. 8702, transverse diameter at triturating 



surface 15.5 



