LIFE HISTORY OF DESMOGXATHUS FUSCA. 



309 



6. The naso-labial groove (gr, Fig. 17) makes its appearance, 

 extending from the latero-ventral border of each external naris 

 until finally, at the completion of metamorphosis, it has reached 

 the border of the upper lip. 



If if 



on 



c 



FIG. 17. (a), (b), and (c), dorsal, ventral, and lateral views respectively of the 

 anterior region of the body of a Desmognathus fusca larva in which metamorphic 

 changes have begun to appear; (d), (e), and (/), dorsal, ventral, and lateral views 

 respectively of the anterior region of the body of a Desmognathus fusca in which the 

 process of metamorphosis is just completed; eyl, eyelids, present only after meta- 

 morphosis; gl, gills which have become slightly blunted and shortened in (a), (b), 

 and (c), and have disappeared altogether except for a slight vestige, glv, at the time 

 of metamorphosis; gr, nasolabial groove, present only after metamorphosis; git, 

 gular fold; //, labial fold which disappears at metamorphosis; ori, orifices of some 

 of the larval acinous glands. Note that with metamorphosis the posterior region 

 of the head becomes relatively narrower. Drawn with Abbe camera. X 4-25- 



7. The labial folds (//, Fig. 17) disappear, and the extent of 

 the mouth opening increases, the lateral angles coming to lie 

 as far back as the posterior angle of the orbit; thus a form of 

 mouth opening adapted to the capture of larger prey, from a 

 terrestrial as well as an aquatic medium, supplants the scooping 

 or sucking apparatus of the aquatic larva. 



