EBPTILBS IN GEOLOGY 157 



Here is a brief review in the form of a key whicli 

 will help to recall the orders only, of these old terrors 

 of the past. 



A. Jaws either toothless or beaklike ; or else with only a pair ot 



tusks or canine teeth evident. Theromorpha. 



AA. Jaws not so. More teeth than two tusks always present. 

 B. Limbs paddle-shaped. 



C, Body snakelike. (Tail longer than neck.) 



Pythonomorpha. 

 CC. Body not snakelike. 



D. Neck very short — much shorter than the tail ; body 



fishlike. Ichthyopterygia. 



DD. Neck longer than tail ; body whalelike. 



Scmropterygia. 

 BB. Limbs not paddle-shaped. 



B, Hind legs longest and largest — often fitted for 

 walking erect ; outer finger not elongated. 



Dinosa/uria, 

 EE. Hind legs not longest; outer finger elongated 

 — fitted for flight. Pterosauria. 



