NO. 1860. A NEW FOSSIL ALLIGATOR FROM MONTANA— OILMORE. 301 



surface is corrugated with depressions radiating from the apex but 

 the base of the enameled surface is smooth. The upper part of the 

 tooth is separated from the gibbous root by a slight 

 constriction at the base of the enamel. 



In the collection of the U. S. National Museum 

 there is a large number of detached teeth from the 

 ''Ceratops beds" of Converse County, Wyoming, 

 which can not be distinguished from those in the 

 specimen under discussion. With them are other 

 teeth which from their minute size and other differ- 

 ences appear to indicate the presence in those beds 

 of one or more undescribed species, but the material 

 is too meager upon which to base a determination. 

 Many of these scattered teeth showed wear on their internal surfaces, 

 thus substantiating the evidence of the Alligatoroid nature of the bite 

 as shown by the wo^-n posterior teeth of the type-specimen. 



Fig L— Twelfth max- 

 illary TOOTH OF 

 Brachychampsa 

 Montana. Natural 

 SIZE, a, Lateral 



view; 6, POSTERIOR 



VIEW. Type-speci- 

 men. 



Principal measurements of mamillary teeth of Brachychampsa montana. Type-specimen. 



Number of tooth... 



Length 



Extent antero-pos- 

 teriorly 



Twelfth. 



mm. 

 11 



12 



