368 BULLETIN 120, UNITED STATES NATIONAL MUSEUM. 



Argentina-Patagonia, for they are much more numerous in botli 

 genera and species in South America than in Australasia. In 

 southern South America the Leptodactylids evolved their charac- 

 teristic parasites, the Zelleriellas. These " southern frogs " passed, 

 probably during the early Miocene, to New Zealand, Tasmania, and 

 Australia, and one species has gone on into Papua. In this spread- 

 ing they gave rise to a number of genera. Northern and southern 

 South America uniting at about the beginning of the Pliocene, the 

 Leptodactylids entered tropical America, becoming there, with the 

 Hylidae, the dominant Anura. Their Zelleriellas are the dominant 

 Opalinidae of tropical America. The Leptodactylids may have 

 migrated westward to Australasia just before New Zealand and 

 Papua became isolated, for they are barely represented in these two 

 regions. It will be of much interest, when the New Zealand and 

 Papuan forms are searched for Opalinids, to see if Zelleriella is 

 found. If it is not found, this will be something of an indication 

 that Zelleriella developed late, just before the migration of Lepto- 

 dactylids to Australia ceased. This is the indication from the al- 

 ready known abundance of Zelleriella in South America and its com- 

 parative scarcity in Australia and Tasmania. 



The Leptodactylids carry Protoopalina and Zelleriella, both bi- 

 nucleated genera. They do not carry any of the multinucleated 

 species, though they have been in contact with Cepedea throughout 

 their American range (excepting only the West Indies) and have 

 met both broad and narrow Opalinae in Central America. On the 

 other hand they have given their Zelleriellas to the Anuran hosts of 

 these multinucleated Opalinids. The Hylidae, however, in contact 

 with the Leptodactylids since the middle Pliocene, have proven 

 almost completely resistant to Zelleriella. The two families Hylidae 

 and Leptodactylidae, having come into contact with all the genera 

 of Opalinidae and nearly all their subgeneric groups of species, have 

 reacted very differently to the several groups of Opalinids, the Lepto- 

 dactylidae completely rejecting all the multinucleated species and 

 being hospitable to the binucleated forms, while the Hylidae, origi- 

 nally containing Protoopalina, reluctantly adopt Zelleriella in but 

 three cases, but readily accept the multinucleated forms. 



The Gastrophrynidae (fig. 229, p. 293). 



The Gastrophrynidae are a fairly large family. Their species are 

 found in tropical America (one form reaching north into southeastern 

 United States) in tropical and southern Africa, in Madagascar, India, 

 Cochin China, and the East Indies (Papua and an adjacent island). 

 In America their parasites are Protoopalinas, Zelleriellas, Cepedeas 



