74 bulletin: museum of comparative zoology. 



(maximum) of 11 mm., while the posterior root has the same antero- 

 posterior diameter but a transverse diameter of 21 mm. The posterior 

 root is, therefore, about twice as thick as the anterior one, and extends 

 much further inward on the palate than the anterior one. It stands 

 somewhat obliquely, as does also the part of the crown which surmounts 

 it. Whether this posterior root is really divided so that the tooth has 

 three roots in all cannot be positively determined from the specimen, 

 which is filled with plaster at this point, but as the root measures 

 24 mm. at the end, it is quite likely that it is divided. Owing to 

 the oblique position of the posterior root, the crown is somewhat trian- 

 gular in horizontal section; the greater part of it, including all the cusps 

 except the very small anterior basal one, is lacking. The antero-posterior 

 length of the crown at the base is 48 mm. ; the vertical length of the 

 anterior root is 41 mm. 



The first molar immediately follows the fourth premolar and is a some- 

 what smaller tooth. It is two-rooted, though the posterior root is some- 

 what twisted and thickened, and a horizontal section of the crown at the 

 base shows a postero-internal enlargement, which gives it somewhat of 

 a triangular form. The antero-posterior breadth of the crown at its 

 base is 41 mm., and its greatest transverse diameter posteriorly, 15 mm. 

 The middle portion of the crown is lacking, but the accessory cusps are 

 nearly intact. These are of about the same size and shape as those of 

 the first premolar, being convex both externally and internally and 

 nearly vertical. There appear to have been two large anterior accessory 

 cusps and a smaller basal one, and three posterior accessory cusps, to- 

 gether with a very small basal one, which probably represents part of 

 the cingulum. The enamel is nearly smooth externally and only moder- 

 ately rugose, with longitudinal lines, internally. At the middle of the 

 tooth externally the distance between the base of the enamel and the 

 margin of the maxilla is 12 mm., but internally the enamel extends 

 farther up. 



The concavity which follows the first molar and appears to represent 

 the alveolus of the second molar is 26 mm. long. As it is undivided, 

 this small tooth probably had the roots consolidated. It is not likely 

 that any additional teeth followed this one. 



The mandible which is included in this collection is so much broken 

 that no detailed description of it seems desirable. The left side is repre- 

 sented by a piece 430 mm. long, extending from the second or third in- 

 cisor to and somewhat beyond the posterior end of the tooth-row. The 

 right side is represented only by fragments from the lower margin of 



