350 



BULLETIN 120, UNITED STATES NATIONAL MUSEUM. 



of the ohtrigona group, and still fewer are virgula-like ; most are of 

 the broad form. We thus see that the narrow species are most 

 abundant in the less modified families of the Anura, and that the 

 broad species are numerous in the Bufonidae, and are dominant in 



the Rani7iae. Several Hylids bear species which are somewhat in- 

 termediate m form between the narrow and broad species. These 

 are all of course secondarily adopted guests, for Opalina was not 

 originally present in tropical South America, the early home of the 

 Hyhdae. (See the next page.) 



