I50 MAURICE G. MEHL 



teeth of the margin below the antorbital vacuity are still preserved, 

 forms a part of the collection. This fragment is undoubtedly 

 Angistorhinus sp. The crown of one of these teeth is well preserved 

 and is almost identical with that shown in Fig. i6, which is one of 

 several teeth found loose in the matrix close to the skull of A. 

 gracilis. The crown of this tooth is 25 mm. long, 20 mm. wide at 

 its greatest width, which is just above the alveolus, and at this same 

 point has a thickness of about 12 mm. The anterior and posterior 

 edges are sharp and very finely serrate, there being three serrations 

 to one millimeter. Of the other teeth figured all but that in Fig. 9 

 have sharp anterior and posterior cutting edges with serrations 

 numbering from fifteen to twenty in five millimeters. In that one, 

 while the anterior and posterior edges are not sharp, the section is 

 oval and it is further differentiated from the others by indications 

 of fluting. In general it resembles the unerupted tooth seen in a 

 section through the rostrum of A . grandis mentioned above. Just 

 where this tooth found its place in the dentition cannot be told. 

 It is the presumption, however, that it is one of the anterior teeth. 

 While the ends of any series that can be formed of these teeth differ 

 widely, they grade into each other in such a way that one would 

 probably not be justified in supposing that such a series could not 

 be found in the jaws of a single individual. Fig. 8, for instance, 

 might well be the anterior tooth in the lower jaw of A. grandis; 

 Fig. 10 is much the same sort of a tooth, but somewhat smaller. 

 Fig. 12 is probably one of the premaxillary teeth. Figs. 11, 14, and 

 16, the middle or posterior maxillary teeth, and Fig. 15, one of the 

 last in the series. The sections of Fig. 13 show well how the 

 approximately circular root suddenly expands into the trenchant 

 edged crown. Such variations as those above show the uncertainty 

 encountered in basing species on a few isolated teeth with our 

 present fragmentary knowledge of the dentition of these forms. 



THE MANDIBLE 



The posterior extremity of each ramus is missing, probably 

 about 200 mm. The part present shows the same characteristics 

 as does the skull when compared with A. grandis, viz., a greater 

 length and more delicate build. The length of the symphysis is 

 approximately 500 mm., considerably greater than in Belodon 



