III.] 



THE COMMON FROG. 



33 



tadpole stage, and all are more or less aquatic when 

 adult. The only exceptions are Pipa, Nototrema, 

 Opisthodelphys, and the Hy lodes before referred to. 

 Very many kinds, however, are, when adult, inhabi- 



i'lG. 14. —Skeleton of the Flying Dragon. 

 (Showing the elongated ribs which support the flitting organ.) 



tants of trees. The question may suggest itself to 

 some, "Are there any which can be said in any 

 sense to be aerial animals .'^" Birds are almost all 



D 



