CLASSIFICATION OF REPTILES. 517 



Uhampliorhynclm.'i had teeth in tlie back of the jaw, tlie 

 ends of the jaws being toothless and probabl}' encased in 

 horny beaks, while in Pteranodon the jaws were toothless. 

 The}' were of diiierent size, some expanding only as much 

 as a sparrow, others with a spread of about nine metres (27 

 feet). They were contemporaries of the Dinosaurs, several 

 forms, discovered by Marsh, occurring in the Cretaceous 

 beds of Kansas. 



Glass V. REPTILIA. 



Air-hreatliing Yertehrates, with limhs usually ending in claws; limbs 

 sometimes aJjsetd, rarely paddle-sliaped ; body scaled ; ribs well developed ; 

 heart in the highest forms four-chambered ; cold blooded ; an incomplete 

 doidile circulatio'i ; oviparous; eggslarge; embryo with an amnion and 

 allantois ; no metamorphosis. 



Order 1. Ophidia. — Body long, cylindrical, usually limbless ; no shoul- 

 der girdle. (Eutsenia.) 



Order 3. Pythonomorpiia. — Extinct, snake-like, limbs paddle-sbaped. 

 (Mosasaurus.) 



Order 3. Lacertilia. — Body with along tail; usually four limbs; mouth 

 not dilatable, the bones of the jaw being firm. (Sceleporus.) 



Order 4. Chelonia. — Body enclosed in a thick shell, within which the 

 head and limbs can be withdrawn. (Testudo.) 



Order .5. Rhynehocephalia. — Lizard-like ; vertebra bi-concave, species 

 mostly extinct. (Sphenodon.) ■ " '■ ^.^ 



Order 6. Ichthyopterygia. — Head large, orbits large ; limbs paddle- 

 shaped ; extinct forms. (Ichthyosaurus. ) 



Order 7. Thermnorpha. — Mammal-like saurians witli solid pelvis and 



shoulder-girdle, and with canines, or toothless and beaked. 



(Dicynodon.) 

 Orders. Sauropterygia, — Extinct colossal saurians, with long necks, 



head of moderate size. (Elasmosaurus.) 

 Order d. Crocodilia. — Thick - scaled ; heart four-chambered. (Croco- 



dilus.) 

 Order 10. Dinosauria. — Colossal extinct saurians, capable of rising 



and resting on the hind legs, and making threetoed tracks. 



(Hadrosaurus.) 

 Order 11. Pterosauria. — Extinct flying saurians, with the fore limbs 



large and a very long ulnar finger; toothed or toothless. 



(Pterodactyl us.) 



