Stewart.] 



( 'retaceous Fisfn s. 



209 



No. 



MAXILLARY. 



PREMAXILLARY. 



Small. 



Medium. 



Large. 



Small. 



Total. 



Small. 



Largo. 



Small. 



Total. 



1 



2 



4 



4 

 4 





5 | 



5 22 

 5 23 

 5 27 

 4 



7+ 

 31 

 32 

 36 



27 

 26 

 6+ 

 35 



27+ 

 32 - L 

 24 ' 

 34 

 23 

 29? 



T " 



2 

 2 

 2 

 2 



1 





2 



2 





2 



3 





2 



4 





2 



88 





2 



132 



1 



5 

 2 



2? 

 2 



3 



5 



"V" 



5 

 5 

 4 



6 

 5 

 4 

 5 

 3 

 4 



20 



26 ' ' 

 19+ 



25+ 

 18 

 26 

 15 



22 ' J . 





155 

 179 



"l" 



2 

 2 

 2 



2 



4 

 2 



866 





3 



275 







•271 > 







3 





3 



287 







301 













353 



3 







2 





2 

















From the above table, it is seen that in not a single instance 

 do the size and arrangement of the teeth exactly agree with 

 either of Cope's species, A', molossus or X. thaumas. The num- 

 ber of teeth is also as varied as is the size and arrangement. 

 Two more or less constant characters are observed in the above 

 table, viz. : The four small teeth on the anterior portion of the 

 maxilla and the two large teeth on the prem axilla which, are the 

 least variable. 



From the above, it is seen that the size and arrangement of 

 the teeth on the maxilla cannot be taken as specific in char- 

 acter. The teeth on the premaxilla show a diversity in size 

 and arrangement which is quite as marked as the size and 

 arrangement of those on the maxilla. While the two large 

 teeth are fairly constant, and in some specimens are about 

 equal in size, yet in other specimens the anterior is much the 

 larger of the two, while in still others the opposite is the case. 



The outer surface of the maxilla is somewhat rugosely 

 marked just above the alveolar border, while the internal sur- 

 face is nearly smooth at this point. This surface curves regu- 

 larly into the superior with no sharp break between the two. 

 pt near the posterior extremity, where the bone beconx - 

 very thin, but the external surface ends abruptly above and 

 forms a slight shelf for the attachment of probably a jugal bone. 



