AND AVES OF NORTH AMERICA. 



PROTEIDA. 



Caudal vertebra? and frontal bones distinct. Inferior pelvic elements not confluent, 



O. o. maxillaria, prefrontalia and nasalia wanting; palatina and pterygoidea present. 



Ethmoid* a vertical plate on each side the cerebral lobes. 



Mandible toothed, teeth plcurodont. Ceratohyals, first pair connate. 



Xo " postorbital and supertemporal bones." 



URODELA. 



Usual cranial bones present, but pterygoids reduced or wanting. 



No "postorbital or supertemporal bones." 



Caudal vertebra? and frontal bones distinct. 



Ethmoid, a vertical plate on each side. 



Mandible dentigerous ; teeth pleurodont. 



Inferior pelvic elements horizontal, in contact; no osseous pubis; ilium suspended to a 



sacral rib. 

 (Mostly no quadratojugal.) 



GYMNOPHIDIA. 



Usual cranial bones present and distinct, including frontals and pterygoids. 



Caudal vertebrae distinct, 



Xo "postorbital or supertemporal bones. "f 



Ethmoid annulus surrounding cerebral lobes. 



Mandible dentigerous ; teeth anchylosed by their bases. J 



(A quadratojugal.) 



* Erroneously called orbitosphenoids by me. Journal Acad. 1866, (on Anura.) 



f When the temporal fossa is overarched, it is by expansion of the maxillary and quadratojugal. (Stannius says. 

 "Squama temporalis.") 



X The teeth of Csecilia are compressed with a trenchant posterior edge, which is crenate after the manner of 

 Megalosaurus, Carcharias, etc. Thus to the numerous genera of Sanrians and Selachians possessing this character, 

 must be added a Batrachian. 



AMEEI. PHILOSO. SOC. — VOL. XIV. 2 



