140 



LABYEINTHODONTIA. 

 Pig. 29. 



Protriton salamandroides. — Greatly enlarged view of the frontal aspect of the 

 skull of a larva, with the characteristic bones shaded ; from the Gaskohle 

 (Lowest Permian) of Bohemia. N, nasal ; F, frontal ; P. a, parietal ; S. 0, 

 supraoccipital ; E.p, epiotic ; S,T, supratempcral ; 8. Q, squamosal P.t.f, 

 postfrontal; Ju, jugal ; P.t.o, postorbital ; im, premaxilla; M.S, maxilla; 

 Q.J, quadratojugal ; Q, quadrate. {After Fritsch.) 



Suborder LABYRINTHODONTIA VERA. 



Crocodiliform Labyrinthodonts, frequently of large size, in which 

 the bodies of the vertebrae in the adult may be either fully ossified, 

 or of a rhachitomous or embolomerous type 1 ; the vertebrae in the 

 young being apparently always of one of the two latter types. 

 Dentine of teeth usually more or less plicated. Cranial bones deeply 

 sculptured, and usually with mucous canals forming a " lyra." No 

 internal gills developed. 



1 In certain genera like Diplospondylus and Cricotus each caudal vertebra 

 consists of a centrum mainly carrying the neural arch, and an equally large 

 and discoidal posterior intercentrum to which the chevrons are united. 

 These intercentra, according to the views of Cope, correspond with the 

 chevron-bearing intercentra of Clepsydrops among the Anomodont Reptilia, and 



