12 University of Michigan 



Matters of considerable general biological interest are sug- 

 gested by the forms described above. A Hyla with the habits 

 but not the structure of an Agalychnis; Phyllobates whose 

 adults are so similar as to have been considered conspecific by 

 three observers but whose tadpoles differ in the most extra- 

 ordinary fashion ; these support the precedence in time of 

 function over form, and the possibility of apparent reversal of 

 the biogenetic law, owing to different larval habits and similar 

 adult habits. 



The case of ]\Iegalophrys seems much like that of Phyllo- 

 bates. Adult and larva live in two different worlds, and while 

 the general environment and habits of most species are more 

 alike as larvae than as adults, the reverse may be, and in these 

 cases undoubtedly is, true. 



The much more profound changes which attend metamor- 

 phosis in frogs than in salamanders lead one to marvel why 

 neoteny is unknown in the former while fairly common in the 

 latter. 



