AMPHIBIA. 285 



limbs lacking ; Siren, the mud eel of southern United States, has 

 jaws armed with horny sheaths. Proteid^, hind limbs present ; 

 jaws with teeth. Proteus of Austrian caves nearly blind ; 

 Necturus (Menobranchus'), the mud puppy of the central United 

 States. 



ORDER 11. DEROTREMATA (CRYPTOBRANCHIA). 



External gills lost, a spiracle on the side of the neck, lead- 

 ing to persistent gill slits. Amphiumid^, limbs rudimentary ; 

 Amphiuma, one species, the congo eel from the southern states. 

 Cryptobranchid^, legs strong ; body salamander-like. Men- 

 opoma (Cryptobranchus'), hell-bender, from U. S. Megalobatra- 

 chiis, giant salamander from Japan, three feet long. Andrias 

 schenchzeri, European miocene, described over one hundred and 

 fifty years ago as a relic of the legendary Noachian deluge. 



ORDER III. SALAMANDRINA (MYCTODERA). 



Gill slits and external gills lost in the adult ; vertebrae fully 

 ossified. Lechriodonta, palatine teeth in a transverse row or 

 posteriorly converging series. Ambly stoma, toothless parasphen- 

 oid, toes four in front, five behind ; many species in U. S. 

 Plethodon, teeth on parasphenoid ; premaxillaries separate. 

 Spelerpes, premaxillaries fused ; Desmognathus, with parasphen- 



FlG. 283. Plethodon erythronotus. 



oid teeth and opisthoccele vertebras. The species of Amblys- 

 toma are remarkable for the length of time that their larvae 

 (^Siredoft) retain their gills, some species (^A. tigrininn) and the 

 axolotl of Mexico breeding in the siredon stage. Most of the 

 lungless salamanders (p. 27) belong in this family. Mecod- 

 ONTA, parasphenoid toothless, palatine teeth in two rows diver- 

 ging behind. Diemyctylus, our common newt. In Europe Triton, 



