PLATE 4 



EXPLANATION OF FIGURES 



Drawings of wax models of the ear capsule. 



30 Larval Desmognathus fusca, 21 mm. long. 



31 Larval Gyrinophilus porphyriticus 82 mm. long. 



32 Adult Gyrinophilus porphyriticus. 



33 Larval Necturus 48 mm. long. 



ABBREVIATIONS 



C^., isolated area of cartilage formed 

 in the fenestral membrane 



Col., stylus columellae (columella) 



Da., dorsal arm of invading isthmus 

 fenestralis 



F., level of the fusion of the stylus col- 

 umellae and cartilage formed inde- 

 pendently in the fenestral membrane 



/./., isthmus fenestralis 



Op., fenestral plate (operculum) 

 Pl.c, portion of columella taking part 

 in the formation of the fenestral plate 

 Ps., parasphenoid 

 Sq., squamosum 



Va., ventral arm of isthmus fenestralis 

 VII, nervus facialis 

 r.j.VII, ramus jugularis facialis 



382 



