506 O. G Marsh — Skull of the Gigantic Ceratopsidce. 



The peculiar armature of the skull has a parallel in the genus 

 Phrynosoma, among the lizards, and Meiolahia, among the 

 turtles, and it is of special interest to find it also represented 

 in the Dinosaurs, just before their extinction 



Such a high specialization of the skull, resulting in its 

 enormous development, profoundly affected the rest of the 

 skeleton. Precisely as the heavy armature dominated the skull, 

 so the huge head gradually overbalanced the body, and must 

 have led to its destruction. As the head increased in size to 

 bear its armor, the neck first of all, then the fore limbs, and 

 later the whole skeleton, was specially modified to support it. 



These features will be discussed in a later communication, 

 but to the present description of the skull should be added the 

 fact that the anterior cervical vertebrae were firmly coossified 

 with each other, an important character not before observed 

 in Dinosaurs. 



The skull represented on the accompanying plate is the type 

 specimen of Triceratops jlabellatus, Marsh. It was found in 

 the Ceratops beds of Wyoming by Mr. J. B Hatcher, who 

 also discovered the type of the genus Ceratops, in the same 

 horizon in Montana. 



