CLASSIFICATION OF VERTEBRA FA 24 



9. Sub-CLASS ICHTHYOSAURIA, Geoffroy 



Quadrate fixed. Vertebrae deeply amphicoelous. Teeth 

 in one groove, or absent. Ribs with capitulum and tuber- 

 eulum. No sternum. Strong abdominal ribs. Neck short. 

 Murine. Limits transformed into hyperphalangeal paddles. 

 Without sacrum. 



Mixosaurus. Muschelkalk, Europe, Spitzbergen. 

 I phthyosaur us. Jurassic and Cretaceous, Europe ; 



Cretaceous, Queensland and New Zealand. 

 Baptanodon. Toothless. Jurassic, Wyoming. 

 Ophthalmosaurus. Teeth rudimentary. Upper Jurassic 

 and Cretaceous, England. 



10. Sub-CLASS PYTHONOMORPHA, Cope 



Long-necked with snake-like body, marine. Anterior and 

 posterior limbs pentadactyle. 



Acrodont teeth on jaws and pterygoids. 



With interparietal foramen. 



Pectoral and pelvic girdles, and sternum present. 



1. Order Dolichosauri. Mandibles with sutural sym- 

 physis. With two sacral vertebrae. 



Acteosaurus. Lower Chalk, Istria. 

 Dolichosaurus. Upper Chalk, England. 

 ? Plioplatecarpus. Upper Chalk, Holland. 



2. Order Mosasauri. Mandibles with ligamentous con- 

 nexion. Without sacrum. Limbs transformed into paddles. 

 Upper Chalk. 



^Mosasaurus. Europe and U.S.A. 



Liodon. N. America, Europe, New Zealand. 

 VPlatecarpus. N. America, New Zealand. 



( lidastes. North America. 



11. Sub-CLASS SAURIA, Brogniart 



Quadrate movable, except in the degraded, burrowing 

 families of Autosauri. Cloacal opening transverse, penes 

 postero-lateral, double. — Since the cretaceous epoch. 



1. Order Autosauri, Haeckel. Right and left mandible 



