324 University Geological Survey of Kansas. 



maxilla, premaxilla and mandible of one individual and the 

 left mandible of another, and was collected from the Niobrara 

 Cretaceous of Wallace county, Kansas, by Mr. E. P. West. 

 The catalogue number of the specimen is 82. 



The maxilla is much larger and more elongated than in S. 

 broadheadi, and the superior border is very thin and more ele- 

 vated just back of the condyle for the palatine than in this 

 form. 



This condyle is very convex ; anterior to it there are two more 

 condyles, which are probably for the ethmoid and vomer. The 

 most posterior of these is broken away, but from the base it 

 appears to have been elevated, as in Saurodon. The anterior 

 condyle is large and triangular in outline, and is bounded in 

 front by a shallow pit not found in the form mentioned above. 

 There are alveoli for thirty-eight teeth, which decrease in size 

 toward the posterior extremity, where they rise but slightly 

 above the alveolar border. 



The premaxilla is more or less plate-like ; externally it is con- 

 vex from before backward and the anterior border is quite ob- 

 lique. There is probably no close connection with its fellow on 

 the opposite side, and the upper portion of the bone is covered 

 with fine lines radiating upward and backward from the ante- 

 rior inferior angle. The teeth seem to be somewhat smaller 

 than those on the maxilla ; alveoli for nine are found. 



The ramus of the mandible decreases more in depth toward 

 the symphysis than in Saurodon. The lower border is very thin, 

 but becomes thicker toward the alveolar border, though it never 

 attains the robustness seen in Xiphactinus. Just back of the 

 symphysis and below the alveolar border there is a prominent 

 swelling, below which there is an elongated ovoid pit, near the 

 position of the Mento-Meckelian ossicle in Amia. The predental 

 surface descends in almost a straight line from the alveolar bor- 

 der, and has numerous bony tubercles internally, probably for 

 ligaments attaching the two jaws. Just beneath the dentary 

 there is a long thin element which seems to be united to it by 

 suture and forms the lower border of the jaw. If this be true, 

 it may represent a new element in the mandible, although more 



