300 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 41. 



Measurements of skull of Bracychampsa montana. Type-specimen. 



mm. 



Distance from anterior angle of orbits to tip of snout 164 



Width of skull at anterior angle of the orbits 157 



Width of skull at maxillo-premaxillary suture 105 



Greatest width of nasal opening 44 



G»eatest longitudinal length of premaxillary 80 



Least width of interorbital bar 26 



Greatest width of nasals 32 



Greatest width of anterior palatine processes 45 



Greatest width of anterior palatine vacuity 33 



Distance from anterior end of palatine vacuity to tip of snout 24 



Length of alveolar border of maxillary 135 



Length of alveolar border of premaxillary 65 



Teeth. — The dental formula of the upper jaw consists of 5 pre- 

 maxillary and 14 maxillary teeth, the total number (38) being the 

 same as found in the upper mandible of many modern alligators. 

 Judging from the size of the alveoli, all of the premaxillary teeth 

 appear to have been of approximately the same size. The teeth 

 still present in the skull are: the bases of three premaxillary teeth, 

 and the third, fourth, fifth, sixth, seventh, ninth, eleventh, and 

 twelfth maxillary teeth on the right side; the roots of the third, fifth, 

 sixth, and seventh, with the tenth and eleventh teeth intact, in the 

 left maxillary. The first three maxillary teeth were relatively small 

 and evidently of about equal size. The fourth is slightly larger than 

 the third; the fifth is larger than the fourth and is the most robust 

 tooth of the anterior dental series; the sixth tooth is slightly smaller 

 than the fifth; the seventh, eighth, ninth, and tenth were quite 

 small, being the weakest of those in the upper mandible; the elev- 

 enth and twelfth were robust, and, judging from the size of the 

 alveoli for the thirteenth and fourteenth, all of these teeth were 

 of approximately the same size. 



The anterior teeth of the maxillary series although somewhat 

 compressed transversely are acutely pointed, and while the fifth is 

 as long as the eleventh and twelfth the anterior posterior extent of 

 the tooth is only a little over half that of the latter. The relative 

 dimensions are well shown in the table of measurements of the teeth 

 given below. 



The posterior teeth of Brachychampsa montana resemble most 

 nearly those figured by Leidy ^ as Bottosaurus Jiarlani from the Cre- 

 taceous of New Jersey.^ 



The crowns of the posterior teeth are somewhat compressed later- 

 ally, mammihform, with outer and inner surfaces separated by a 

 somewhat obscure carinas which extends from the subacute apex to 

 the base of the corrugated surface as shown in figure 1. The upper 



I Smithsonian Contributions to Knowledge, vol. 18, pi. 18, figs. 11-14. 



