572 Bulletin America7i Museum of Natural History. [Vol. XIX, 



sulcus, a little in front of the middle ; the outer face is marked 

 by a corresponding sulcus opposite but not quite so deep. 

 These sulci, on opposite sides, form the constriction that 

 divides the tooth into two lobes. Its greatest length is 

 oblique to the line of the series. 



The third molar is bilobed but somewhat modified from the 

 preceding. The anterior side is gently convex with a faint 

 indication of a groove in the middle. The inner side is short- 

 est with a deep sulcus near its middle, while the outer side is 

 longest with a less defined sulcus. The outer anterior angle 

 is convex, as in the preceding tooth, but much broader. The 

 greatest diameter is oblique to the series. 



The fourth molar is shaped like the figure 8; the anterior 

 lobe is larger and slightly oblique to the dental series. The an- 

 terior side is convex ; the outer and the inner sides are nearly 

 parallel, and near the middle of each is a sulcus that forms the 

 constriction dividing the tooth into two lobes; the posterior 

 side is convex but not as wide as the anterior side. The 

 greatest diameter is parallel to the series. The plane of the 

 alveolar outlet slopes from without, inwards and downwards; 

 the space separating the alveoli of the first two is about twice 

 that separating the succeeding teeth. 



The maxillary part of the palate is of a triangular form with 

 the base turned forward ; gently convex from the palatines 

 forward to a line connecting the anterior borders of the first 

 molars, from which point it bends downward to the end of the 

 maxillaries. The surface is pitted with several rows of small 

 deep foramina parallel to the alveoli, and the anterior palatine 

 foramina are situated on either side of the median premaxil- 

 lary notch, passing forward, in two shallow grooves on each 

 side, to small notches on the inner anterior border. The 

 median maxillary suture presents a raised ridge, on either side 

 of which is a shallow groove extending from the antepenulti- 

 mate molar back to the palatines. The anterior border of 

 the m-axillaries presents two rounded thickened surfaces, 

 separated by a deep median notch, for the articulation of the 

 premaxillaries , which must have been large and movable, 

 indicating a large prehensile lip. Directly in front of the 



