18 ANATOMY OF VERTEBKATES. 



Order XXII. DINOSAURIA. (Extinct.) 



Cervical arid anterior dorsal vertebra? with par- and di-apo- 

 physes, articulating with bifurcate ribs ; a few anterior vertebrae 

 more or less convex in front and cupped behind ; the rest 

 with flat or slightly concave articular ends ; dorsal vertebrae with 

 a neural platform ; sacral vertebrae exceeding two in number ; 

 body supported on four strong, ambulatory, unguiculate limbs. 

 Skin in some armed by bony scutes. Teeth confined to upper 

 and lower jaws ; implanted in sockets. Ventricle of heart double 

 (inferential). 



Genera, Iguanodon, Scelidosaurus, Megalosaurus. 



Order XXIII. PTEROSAUKIA. (Extinct.) 



Pectoral members, by the elongation of the anti-brachium 

 and fifth digit, adapted for flight. Vertebras proco2lian ; those 

 of the neck very large, those of the pelvis small. Anterior 

 trunk-ribs with bifurcate heads. Most of the bones pneumatic. 

 Head large ; jaws long, and armed with teeth. Ventricle of 

 heart double (inferential). 



Genera, Dimorphodon , Hamplwrliynclius, Pterodactylus. 



