Fio. 120. — Metamorphosis of the Fro;;. 1, tadpdle just hatched, dorsal aspect; 

 3-3, older tadjioles, side view; 4, later tadpole, dorsal view showinp; cutaneous 

 gills at niaxiuium development; 5, later stage, ventral view, showing degeneration 

 of cutaneous gills and development of operculum; 6', older tadpole, left side, 

 showing single opening of operculum; 7, older stage, right side, showing hind leg 

 and anus; 8 and 10, lateral views of two later stages showing development of hind 

 legs; 9, dissection of tadpole to show internal gills, spiral intestine, and anterior 

 legs developed within operculum; 11, advanced tadpole just before metamorpho- 

 sis; 12, 13, 1/f, stages in metamorphosis, showing gradual resorption of tail; 15, 

 juvenile frog after metamorphosis. (From Weysse, after Leuekart-Nitsche wall 

 chart.) 



20S 



