CLA SSIFICA TION OF VER TEBRA TA 23 



Hadrosaurus and Diclonius. Upper Cretaceous, U.S.A. 



? Ornithomimus. Upper Cretaceous, Colorado. 

 4. Order Ceratopsia, Marsh. Pubes simple, with sym- 

 physis. Pentadactyle, quadrupedous. Maxilla and mandible 

 with a toothless rostrale and predentale. With dermal armour. 



Ceratops and Triceratops. Cretaceous, Europe and U.S.A. 



7. Sub-CLASS PTEEOSAUEIA, Kaup 



Stereospondylous. Quadrate fixed. Anterior limbs trans- 

 formed into wings, the enormously elongated ulnar finger 

 carrying the patagium. 



1. Sub-order PTEEODACTYLI. With alveolar teeth. 

 Dimorphodon. Lias, England. 



Pterodactylus and Ehamphorhynchus. Upper Jurassic, 



Europe. 

 Ornithocheirus. Cretaceous, England. 



2. Sub-order PTEEANODONTES. Without teeth. 

 Scapula articulating with spinous processes of dorsal vertebrae. 



Pteranodon. Cretaceous, Kansas. 



8. Sub-CLASS PLESIOSAUEIA, Eitzinger 



Quadrate fixed. Alveolar teeth. Thoracic ribs without 

 tuberculum. Strong abdominal ribs. One or more sacral 

 vertebrae. No sternum. Neck mostly long. Aquatic. 



1. Order Mesosauri, Boulenger. Pentadactyle, not more 

 than five phalanges. Vertebrae with persistent notochordal 

 canal. Four sacral vertebrae. 



Mesosaurus. Trias, S. Africa and Brazil. 



2. Order Nothosauri, Boulenger. Pentadactyle walking , 

 and swimming limbs, with not more than five phalanges. 

 Vertebrae solid. 



Nothosaurus. Muschelkalk, Germany. 

 Lariosaurus. Upper Trias, fresh water, Lombardy. 



3. Order Plesiosauri. Limbs transformed into hyper- 

 phalangeal paddles. Vertebrae solid. Europe, from the 

 Ehaetic to the upper Chalk, Marine. 



Plesiosaurus, Pliosaurus, Polyptychodon. 



