CHORDATA — VERTEBRATA — REPTILES 355 



Reptilia are subdivided into the following orders : — 



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1. Rhynchocephalia 355 



2. Anomodontia 355 



3. Sauropterygia 356 



4. Ichthyopterygia 358 



5. Dinosauria 359 



6. Pterosauria 364 



7. Crocodilia 365 



8. Chelonia 365 



9. Squamata 367 



Order i, Rhynchocephalia 



Lizard-like, scaly reptiles with biconcave vertebrae and fre- 

 quently with a beak at the end of the skull (whence the name 

 from Greek rhynchos, a beak, + cephale, head). 



The Rhynchocephalia are known from the Permian to the 

 present, with maximum development in the Triassic. The sole 

 survivor is the small Hatteria (or Sphenodon) now living on 

 two or three small islands off the coast of New Zealand. This 

 is similar to the fossil Paleohatteria from the Permian of Europe, 

 which in its turn has many points of similarity with the amphib- 

 ian order, Stegocephalia. The survival of the very primitive 

 Hatteria is probably primarily due to its removal in the Austra- 

 lian region from competition with the higher mammals, and 

 secondarily to its burrow life, which withdraws it still further 

 from competition. The Rhynchocephalia unite pretty closely 

 the orders Squamata, Crocodilia and Dinosauria; in other 

 words, they are generalized types. 



Order 2, Anomodonlia {Theromorpha) 



Extinct land reptiles with limbs adapted to the habitual 

 support of the body. Pineal foramen always present. Teeth 

 usually lodged in sockets and varying from an arrangement in 



