154 MAURICE G. MEHL 



in the upper dentition. In the downward portion proper of the 

 premaxilla there are two alveolae of a size and shape to indicate 

 long conical teeth of about 21 mm. diameter at the base. Immedi- 

 ately behind the down-turned portion is another large alveolus, 

 about 15 mm. in diameter. This is followed closely by a fourth, 

 considerably smaller, alveolus. Between the fourth and fifth 

 alveolae is a conspicuous space. This is marked on one pre- 

 maxilla by a depression as though for the reception of a tooth 

 from the lower jaw. The following alveolae, with the exception 

 of the last few on the premaxilla, increase gradually in size from 

 about 6 mm. to 12 mm. There is a marked lateral expansion of the 

 rostrum near the posterior end of the premaxillae for the accommo- 

 dation of three or four exceptionally large teeth. The root of one 

 of these is preserved and measures 13 mm. in diameter. The 

 crown preserved in the maxilla series as mentioned above is laterally 

 compressed with sharp, slightly serrate, anterior and posterior 

 edges. 



It would seem that the dentition was very much Hke that of 

 Machaeroprosopus validus,^ greatly enlarged seizing teeth in the 

 front, grading through smaller, sharp, conical to laterally com- 

 pressed shcing teeth behind. The space between the fourth and 

 fifth alveolae indicates likewise a shorter jaw with large terminal 

 teeth directed sidewise. 



RELATIONSHIPS AND HABITS 



Of the close afi&nity between the present specimen and that 

 described as Machaeroprosopus validus^ there can be no doubt; 

 both skulls are crested forms of the "broken outline" type; both 

 have the depressed posterior border of the supratemporal openings ; 

 and both have enlarged, conical terminal teeth with laterally 

 compressed, sharp-edged, slicing teeth behind. The skulls differ 

 in so many minor points, however, that they can scarcely be placed 

 in the same species. The writer will designate the present form, 

 therefore, as Machaeroprosopus andersoni in honor of Professor 

 Anderson, who presented the material to the University of Chicago. 



' Mehl, Bull. Univ. of Oklahoma, op. cit., p. 20. 

 ^Ibid. 



