1913] Merriam : Tapir Remains from Pacific Coast Region 171 



cingulum. The posterior cingulum is narrow transversely. On 

 the anterior side of the crown there are two basal ridges. One 

 is median and is partly continent with the anterior ridge of the 

 protoconid. The other anterior basal ridge lies below and in 

 front of the one just described, and forms a distinct shelf on the 

 external side of the anterior end of the tooth. It reaches nearly 

 to the extreme outer border of the tooth. On both the outer and 

 inner sides of the tooth small tubercles are developed between 

 the bases of the anterior and posterior transverse ridges. The 

 inner tubercle is very faint, but the outer one is a noticeable 

 feature of the tooth (see figs, la to lc). 



The specimen just described does not differ greatly from M 2 

 and M 3 of Elasmognathus bairdii. It is distinguished by the 

 slightly larger anteroposterior diameter of the anterior basal 

 ridges, and by the smaller size of the external basal tubercle 

 between the metalophid and hypolophid. In the only specimen 

 of E. bairdii available for comparison the posterior molars are 

 somewhat worn and the characters of the transverse ridges are 

 not as clearly shown as in the fossil specimen. 



In such figures of the dentition of Tapirus terrestris as are 

 available, the characters of M 3 seem very close to those of the 

 fossil from California, though the details of form are not clearly 

 discernible on any figures of T. terrestris at hand. 



The type specimen of Tapirus haysii figured by Leidy 3 seems 

 to show anterior and posterior cingula, and an external basal 

 tubercle between the metalophid and hypolophid. The width or 

 transverse diameter of the tooth is, however, relatively much 

 greater comp;ired with the length or anteroposterior diameter, the 

 relation being as 22.3 : 27 in T. haysii, and 17.8 : 25.3 in the Cali- 

 fornia specimen. As the teeth compared are both presumed to 

 represent M 2 of the left side, it would seem that the considerable 

 variation in width, amounting to at least twelve per cent, may 

 represent specific or subspecific difference. In Elasmognathus 

 bairdii the ratio of width to length is intermediate between that 

 in the California specimen and that in the type of T. haysii. 



a Leidy, J., in Holmes, Post-Pleioeene Fossils of South Carolina, pi. 17, 

 figs. 7 and 8, 1860. 



