Dr. Baron Francis Nopcm — Craterosaurus. 483 



Scelidosaurus, from all well-known Acanthoj^holididse (viz. Polacanthus, X 

 Acanthopholis, Struthiosaurus, and StegocerasJ^fvom the Nodosauridge 

 (like Ankylosaurus),^ and even from the Stegosaurid genus Omosaurus. 

 Altogether Craterosaurus shows a striking resemblance to the genus 

 Stegosaurus, and were it not for the fact that it seems hazardous to 

 determine the exact position of so poor a " medal of creation ", and 

 that no Stegosaur has ever been found in so young a deposit as the 

 Potton Sand, Craterosaurus might be considered as a synonym of 



Fig. 2. Stegosaurus sp. ; dorsal vertebra in right side-view (A) and 

 back view (B), one-quarter nat. size. Upper Jurassic : Medicine Bend, 

 Wyoming, U.S.A. [British Museum, No. E. 3216.] d. diapophysis ; 

 n. neural spine ; pa. parapophysis ; pr.z. prse-zygapophysis ; pt.z. post- 

 zygapophysis. 



Stegosaurus ; under the circumstances, however, it seems best to 

 retain provisionally the name given by Seeley. 



Great as Professor Seeley' s error in the determination of Craterosaurus 

 seems to be in the light of our present knowledge, it must be 

 remembered that the fossil was described at a time when one knew 



■• The difference between the Acanthopholididse and the Nodosauridte 

 ( = Ankylosauridse) is best seen in the structure of the cranium. Details will 

 be published on some other occasion. 



