A SYNOPTIC CLASSIFICATION OF THE REPTILIA 213 



single coracoid; no clei thrum. Phalangeal formula primitive. Often 

 reduced postaxially. 



12. ? Proterosuchia. Skull elongate, with palatal teeth; an antor- 

 bital vacuity. Skull only known. Triassic. 



13. ?Eosuchia. No antorbital vacuity^; interparietal and tabulars 

 present; a parietal foramen. Only skull known. Upper Permian. 



A. DIAPTOSAURIA. No antorbital foramen in skull; no supra- 

 temporal, tabulars or interparietals; palate with teeth. Vertebrae 

 amphicoelous. Dorsal ribs articulating with intercentral space or 

 centrum and arch, holocephalous. 



14. Rhynchocephalia. Teeth protacrodont or acrodont. 



A. Rhynchosauria. Skull broad, with decurved premaxillae 

 and crushing teeth on palate. No epicondylar foramina; 

 pubo-ischiatic opening small. Littoral reptiles. Upper 

 Triassic. 



B. Sphenodontia. Premaxillae beak-Uke; pelvis with large 

 pubo-ischiatic vacuity; an entepicondylar foramen; dorsal 

 intercentra persistent. Littoral reptiles. Upper Jurassic to 

 Recent. 



C. Choristodera. Face elongate, the nares terminal; no 

 pubo-ischiatic vacuity; teeth labyrinthine. Subaquatic. 

 Uppermost Cretaceous and Lowermost Eocene. 



I). ? Thalattosauria. Skull elongate, with external nares 

 posterior. Ribs attached by single head to centrum. Limbs 

 paddle-Hke. Imperfectly known. Aquatic. Triassic. 



AA. ARCHOSA URIA . Dorsal ribs, anteriorly at least, articulating with 

 arch only, dichocephalous; no teeth on palate; no parietal foramen; 

 no supra temporal, interparietal, or tabulars; vertebrae variable; 

 dorsal intercentra not persistent; usually an antorbital opening. 

 Typically with large pubo-ischiatic vacuity. 



15. Parasuchia. Pelvis more or less plate-like with small pubo-ischi- 

 atic vacuity; vertebrae amphicoelous; no false palate; phalanges 

 not reduced; body with dermal scutes. 



A. PsEUDOSUCHiA. External and internal nares near extremity 

 of face; legs elongate, the epipodials long. Cursorial reptiles. 

 Triassic. 



B. Pelycosimia. External and internal nares terminal. Legs 

 short and stout. Terrestrial or marsh reptiles. Triassic. 



C. Phytosauria. External and internal nares remote from 

 extremity of slender face. Triassic. 



16. Crocodilia. Pubes excluded from acetabulum, not meeting in 

 ventral symphysis. A secondary palate. External nares termi- 

 nal; vertebrae amphicoelous or procoelous; postaxial digits 

 reduced. 



A. EusuCHiA. With dermal plates; no sclerotic plates. Am- 

 phibious. Jurassic to Recent. 



^ [According to Broom, a well-preserved antorbital vacuity is present. — Ed.] 



