104 University of Kansas Geological Survey. 



section in front of the teeth, the tip obtuse. The teeth are 

 relatively smaller than in the other genera. Just back of the 

 posterior pair the sutural border runs a short distance rectan- 

 gularly upward. Front this angle, the sides run obliquely 

 backward to the anterior angle of the nares. The intermaxil- 

 lary portion is very broad and long, more than twice as wide in 

 front as behind. The surface above throughout is convex 

 and smooth, without carina or depression. Posteriorly, to the 

 anterior end of the nares, the internarial portion narrows rap- 

 idly, but is much thicker and stronger in the narrowest part 

 than is the case in either of the other genera. The conjoined 

 nasals broaden as in the other genera to overlap the anterior 

 end of the frontal, but extend much further back, beyond the 

 nares. The free internarial portion of the conjoined bone is 

 only a trifle longer than the intermaxillary portion. On the 

 under side the ridge separating the anterior teeth divides at 

 their posterior part into two branches, between which are in- 

 serted the thin, vertical and contiguous anterior ends of the 

 vomers. The thin plate or ridge continues on each side into a 

 tongue-like process, vertically flattened and suturally united in 

 a shallow groove on the outer side of each vomer as far back as 

 the posterior part of the second tooth, articulating on the inner 

 side of the maxilla at the base of the first tooth. 



Vomers. 



The vomers in Mosasaurus are very slender, and are in appo- 

 sition throughout, or for the most part. Near the front end, the 

 short, vertical, articular face unites with the maxilla opposite 

 the second tooth. Just back of the articular surface there is a 

 small elongate oval opening left on each side between the con- 

 stricted vomer and the emargination of the horizontal plate of 

 the maxilla. The vomers, as far back as the eighth or ninth 

 teeth, are very narrow below, the surfaces somewhat obliquely 

 placed. Posteriorly they seem to join by a long, squamous 

 suture with the anterior prolongation of the palatines. 



The vomers in Clidastes are evidently quite like what they are 



