72 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



third incisor when the mouth was shut. A similar concavity behind 

 the tooth, about 28 mm. above the palatal surface, indicates the position 

 of the apex of the lower canine. That it is higher up than the preceding 

 concavity shows that the canine is longer than the third incisor in this 

 species. 



Following the third upper incisor, there is a deep concavity in the 

 prernaxilla, in which the anterior end of the maxilla rested. The latter 

 bone is broken anteriorly, and hence nothing can be determined regard- 

 ing the form, or exact position, of the canine. The most anterior portion 

 of the maxilla preserved contains, as already mentioned, the alveolus of 

 a large tooth, which was presumably the first upper premolar, and fol- 

 lowing it a still larger tooth in its socket which I consider the second 

 premolar. The alveolus of the first premolar is pyriform, and has a 

 longitudinal diameter of 39 mm. and a transverse diameter of 21 mm. 

 Immediately in front of it, where the bone is broken off, is a concavity 

 not less than 18 mm. deep, and inclined inward and backward, which 

 I was at first disposed to regard as the anterior root of the first premolar. 

 After close examination I am of the opinion that it represents the im- 

 pression of the apex of the first lower premolar. The bottom of it lies 

 a little outside the line of the long axis of the large alveolus which suc- 

 ceeds it. 



The first upper premolar was probably a single-rooted tooth, as the 

 alveolar cavity narrows rapidly upward. The distance between this 

 tooth and the second upper premolar is 16 mm. In the interval be- 

 tween the two teeth and a little within the line of the long axis of the 

 former is a rather shallow concavity, which represents the impression 

 of the apex of the second lower premolar. 



The second upper premolar of the left side, a two-rooted tooth, has the 

 following dimensions (Plate 1, figure 4) : Depth from apex of crown to 

 end of anterior root, 1 71 mm. ; to end of posterior root, 1 71 ; breadth of 

 crown at base, 52 ; length of anterior edge of principal cusp, 22 ; length 

 of posterior edge of the same, 19 ; antero-posterior bi'eadth of the an- 

 terior root, on the line of anterior base of the crown, 20 ; antero- 

 posterior breadth of posterior root, on line of posterior base of crown, 

 25; transverse breadth of the anterior root at the same point, 14; 

 transverse breadth of the posterior root at the same point, 15 ; distance 

 between the apex of the principal cusp and the point of junction of the 

 two roots, 34. 



The greatest height of the enamel at the middle of the crown as pre- 



1 Slightly broken. 



