First Expedition to Kansas Chalk 53 



crum, pressed the living prey firmly upon these 

 teeth so that it could not come forward and escape. 

 Then notice the ball-and-socket joint just back of the 

 tooth-bearing bone or dentary, of the lower jaw. 

 After the wriggling, struggling prey had been fas- 

 tened on the teeth in the roof of the mouth, the 

 mandibles were shortened by a spreading of this cen- 

 tral joint, and the victim was forcibly pushed down 

 the throat. 



The species Clidastes velox of these Kansas mosa- 

 saurs, was, as its name indicates, very agile, with 

 beautiful bones of so firm a texture that they have 

 suffered less than any of the other fossil vertebrates 

 from the vast pressure to which they have been 

 subjected, not only from the enormous amount of 

 material that has been heaped above them, but from 

 the still more powerful upward push which has 

 raised their burial-place three thousand feet above 

 sea level. 



I sent one very beautiful specimen of Clidastes 

 to Vassar College; so complete, in fact, that it can 

 be made into a panel mount. 



I think no artist has more fully appreciated what 

 these great reptiles must have been when alive than 

 Mr. Sidney Prentice, now of the Carnegie Museum, 

 whose beautiful restoration, made to illustrate Dr. 

 Williston's work on Kansas Mosasaurs, is here re- 

 produced (Fig. nb). I am under obligations to him 



