114 THE AMERICAN NATURALIST. [Vol. XXXVIII. 



vertebrae, (2) Symphypoda Cope for the smaller types with 

 hollow, cylindrical vertebrae. 



The Opisthocoelia of Owen although proposed as a ' suborder ' 

 of Crocodilia appears to enjoy priority of definition over the 

 Cetiosauria of Seeley or the Sauropoda of Marsh.' 



Similarly the Orthopoda of Cope is distinctively prior to the 

 admirable term Predentata of Marsh. In the selection of these 

 terms we cannot be governed by our preferences ; we are bound 

 to stand by the law of priority. 



VI. Superorder Squamata Oppel. 



This superorder ranks in value with the Diaptosauria and 

 Dinosauria inasmuch as it includes the very wide adaptive radia- 

 tion of three groups of animals which were undoubtedly closely 

 related in origin, namely: (i) Lacertilia, (2) Mosasauria, (3) 

 Ophidia. 



The radiation of the Mosasauria from the Lacertilia is analo- 

 gous to that which we have observed occurring independently in 

 three orders of the Diaptosauria, namely, the Proganosauria, the 

 Choristodera, and the aquatic Rhynchocephalia of the Jurassic. 



Vn. Order Ptkrosal-ri A Kaup. 



here IS no question as to the Diapsidan relationships of the 

 Pterosauna and as to their original derivation from Rhyncho- 

 cephaloid types, although their specialization has carried them to a 

 very groat extreme of separation from any known Diaptosauria. 



that the reclassification of the Reptilia here outlined, 

 rder of arrangement here adopted will be found to 

 len- study. Memoirs now in preparation by Broom on 

 lophonia, by Case on the Pelycosauria, by Brown on 



