CLASSIFICATION OF VERTEBRATA 24 



9. Sub-CLASS ICHTHYOSAURIA, Geoffrey 



Quadrate fixed. Vertebrae deeply amphicoelous. Teeth 

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

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

 Marine. Limbs transformed into hyperphalangeal paddles. 

 Without sacrum. 



Mixosaurus. Muschelkalk, Europe, Spitzbergen. 

 Ichthyosaurus. 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. 

 Platecarpus. N. America, New Zealand. 

 Clidastes. North America. 



11. Sub-CLASS SAUPJA, 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 



