Stewart.] 



Cretaceous Fishes. 



271 



Maxilla: Distance from anterior condyle to posterior extremity, 338 mm. 



Depth of bone at posterior condyle 92 " 



Distance between the two anterior condyles 44 " 



Length of alveolar border •245 ' • 



Thickness at posterior condyle 35 " 



Premaxilla : Length of lower border G7 " 



Depth 112 " 



A table of measurements showing the great variation in size 

 of the maxillae in different individuals is given : 







MAXILL.E. 







No. 



Length 

 from pre- 

 maxilla ry. 



Depth at 

 posterior 

 condyle. 



No. 



Length 

 from pre- 

 maxillary. 



Depth at 

 posterior 

 condyle. 



1 





102 

 111 

 119 



78 



92 , 



88.5 



98 



83.5 



179 

 266 

 275 

 279 

 287 

 301 

 353 



1S3 



68 



2 



260+ 

 314 

 216.5 

 273.5 



84 



3 



4 



88 



127 



220+ 



263 



220 



94 

 90 

 80 

 90 



132 



155 



261 

 205+ 



219+ 



75 



The dentary is deep, strongly built, and not incurved ante- 

 riorly. The alveolar border is slightly concave, and bears two 

 large teeth at the anterior extremity, which are usually sepa- 

 rated by a transverse groove from those following. Just back of 

 this groove there are three or four large teeth which are followed 

 by a number of medium-sized and small ones, the diversity in 

 size and arrangement of which is shown in the table following 

 this description. The teeth are all strongly implanted, with 

 straight conical crowns, non-striate except under the microscope, 

 and are cylindric in cross-section. The symphyseal portion 

 slopes strongly backward and is very thick, but the principal 

 articulation with the opposite jaw seems to be on the internal 

 side, where the bone is very rugose. The lower border is rather 

 sharp, and usually has a row of large nutrient foramina leading 

 inward and forward just above it. The internal side is broadly 

 vertically concave in the posterior portion, but becomes much 

 less -o anteriorly. At the end of the alveolar border the bone 

 is projected upward and slightly outward into a weak coronoid 

 process 



