146 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 105 



The depth of the left mandible in its present condition at the 

 posteriormost alveola was approximately 40 mm., although crushing 

 may have distorted the ramus to some extent. The opposite free 

 posterior portions of the mandibles come together at an acute angle 

 (25°) at the symphysis. 



Measurements of mandibles (in millimeters) 



Greatest length of ankylosed symphyseal portion of mandibular 



rami 147. 



Greatest length of right mandibular ramus, including symphysis 170. 

 Transverse diameter of ankylosed symphysis at posterior end 43. 



Vertical diameter of ankylosed symphysis at level of posterior end 27. 

 Transverse diameter of ankylosed symphysis 20 mm. behind ante- 

 rior end 28. 

 Vertical diameter of ankylosed symphysis 20 mm. behind anterior 



end 23. 



Interval containing 14 alveolae in left mandibular ramus (count- 

 ing forward from hindmost) 146. 



ROSTRUM 



The rostrum (pi. 17, fig. 3) is represented by a 136 mm. piece of 

 the posterior palatal portion of the right maxillary, a 70 mm. piece 

 of the right premaxiUary, and a 115 mm. piece of the left premaxillary. 

 The roots of three teeth are in place in the maxUlary, but lack crowns. 

 On this portion of the maxiUary there were at least six alveolae 

 anterior to these teeth and three alveolae posterior to them. In- 

 asmuch as the inner margin of this right maxUlary is complete, the 

 width of the rostrum at the level of the anterior ends of the palatine 

 bones cam be estimated as approximately 85 mm. The tapering 

 maxillary fragment also indicates that the palate narrowed rapidly 

 anteriorly. 



TEETH 



These teeth (pis. 20, 21) are somewhat similar to those of Del- 

 phinodon dividum described and figured by True (1912, pp. 171-174, 

 pi. 19, figs. 1, 2; pi. 26, figs. 1-20). They differ in part from the 

 teeth of D. dividum in being larger and in having the crowns of the 

 long anterior teeth more noticeably compressed anteroposteriorly. 

 Further comparison is not necessary with most of the species de- 

 scribed from the Miocene of either Maryland or Virginia. 



There are 54 fairly complete teeth, though none are entirely so. 

 The enamel on the inner surface of the crowns is somewhat variable in 

 ornamentation. Nevertheless, this ornamentation of the enamel on 

 the crown, with other characters, serve as an indication of the position 

 of the teeth in the jaws. They group themselves naturally as 

 follows : 



