152 BULLETIN 16 9, UNITED STATES NATIONAL MUSEUM 



The symphysis is short, unfused, and relatively deep. There is a 

 larger mental foramen beneath P2 or the posterior part of the canine 

 and another, smaller, beneath P4. The dental foramen was far back 

 of the molars and slightly below the alveolar level. The angular 

 process is not completely preserved in any case but was directed 

 decidedly downward, as well as backward, and evidently was strong 

 and more or less styliform. Condyle and coronoid are not preserved. 



The upper canine is represented only by part of its alveolus in one 

 specimen (9540). This suggests that it was strongly reduced, the 

 portion of alveolus preserved indicating a root not larger than the pos- 

 terior root of P-. P^~^ are known only from alveoli. Each had a 

 small anterior and large posterior root. On P^ the disparity is greater, 

 and the posterior root more transverse, but even it apparently does not 

 have a third root, and the inner heel, or protocone, must have been 

 small. 



P* is a large, transverse tooth with three separate roots. The high 

 outer cusp, paracone or amphicone, is vaguely triangular and is 

 single, only very slight inner and outer vertical depressions suggesting 

 the incipient appearance of a metacone on its posterior slope. There 

 is a small, distinct parastyle and a much less distinct metastyle higher 

 on the crown than the parastyle. The posterior half of the outer face 

 has a narrow, sharp basal cingulum. The protocone is large and 

 definite but lower than the amphicone, and its apex is anterior to a 

 median transverse line across the tooth. From it a small sharp, 

 cingular crest runs to the parastyle. Another crest falls away directly 

 posteriorly from its apex to the expanded posterointernal angle of the 

 crown, where it turns nearly at right angles and becomes a well- 

 developed but simple posterior cingulum. A minute, isolated cuspule 

 appears in the position of a metaconule. 



M^ and jSP are almost identical in structure, differing only in outline 

 and proportions. Paracone and metacone are strong, distinct, and 

 nearly equal, the paracone very slightly larger. There is a strong 

 external cingulum, rising at the anteroexternal comer without definitely 

 forming a parastyle cusp. The metastyle is likewise small and vague 

 but is more nearly cuspidate. There is no trace of a mesostyle. The 

 inner face of the tooth is flattened and has a distinct, median, vertical 

 groove that divides it into two basal lobes, the posterior lobe being on 

 M' slightly and on M^ distinctly larger. These lobes, however, do not 

 correspond to distinct cusps. There is only one cusp, the protocone, 

 which is on the posterior lobe very near the distal end of the groove. 

 Although larger, the protocone has the same structure as on P* with 

 the addition of a ridge to the metaconule, departing not from the 

 apex but from the posteroexternal slope. The anteroexternal ridge, 

 as on P^, runs to the anteroexternal comer, or to the parastyle (here 

 less distinct) but at its midpoint here has a cuspule, a protoconule, the 



