860 Illinois State Lahoratonj of Natural Hisfori/. 



Family PLETHODONTID^. 



No branchial tufts; openings closed in adults. With four 

 legs, fingers four, toes four or five. Palatine series of teeth 

 more or less transverse. Eyelids present. Teeth on the max- 

 illaries and preraaxillaries. Parasphenoid teeth present. The 

 tongue attached by a slender median pedicel and free all round, 

 or attached by a median strip which extends from the anterior 

 margin to about the middle, the tongue being thus free at the 

 sides and behind. Palatines not prolonged over the parasphe- 

 noid. Pterygoids wanting. Prefrontals present, not prolonged 

 and embracing frontals. Premaxillaries generally embracing 

 a fontanel. Occipital condyles sessile. Carpus and tarsus car- 

 tilaginous. Vertebrge amphicoelian. 



SYNOPSIS OF ILLINOIS GENERA. 



1 (2). Tongue attached by a pedicel and free all round. One 



premaxillary bone, with a fontanel. Fingers four; 

 toes five, free. Cranial bones ossified Spelerpes 



2 (1 ). Tongue attached by a median strip and free at the sides 



and behind. Two premaxillary bones 3. 



3 (4). Fingers four; toes five. Parietals ossified .. Plethodon. 



4 (3). Fingers four; toes four. Parietals ossified. 



Hkmidactylium. 



Spelerpes, Ivaf. 



Rafinesque, Atlantic .lour. 1832, 1., p. 22. 



Hoffmann, Bronn's Thier-Keich, VI., Amphibien, p. 070. 



Cope, Proc. Acad. Nat. Sci. Phila., 186<.», p. 104. 



Tongue small, circular in outline, attached by a pedicel, 

 free at its margins. Vomerine teeth more or less transverse, 

 interrupted medially or continuing to the parasphenoid patches; 

 the latter in two large posteriorly divergent patches. Costal 

 grooves well marked. Tail long, with no membranes. Species 

 mostly small. 



