366 bulletijst 120, united states national museum, 



:ible evidence of a connection from this land strip to eastern North 

 America across the Sonoran region of northern Mexico and south- 

 western United States. Hylids may therefore have been in 

 Central America and eastern United States since the earlier Tertiary. 

 This would be in agreement with the fact that these regions show 

 several genera and numerous species not found in South America. 

 This diversification might, however, have occurred since the early 

 Pliocene in the case of such a vigorous family as the Hylidae. 



Three (or four?) species, or subspecies, of Hyla are known from 

 eastern Asia, Europe, and northern Africa. ?Iyla arborea of Europe 

 carries a species of narrow Opalina^ 0. oMrigona^ and the same" 

 Opalina is found in the two subspecies of Hyla arhorea examined 

 {savignyi from Asia Minor and japonica from Japan). This is evi- 

 dence that the Euro- Asian Hylas came from America. This must 

 have been a comparatively recent migration, for it doubtless occurred 

 after the broad Opalinas had passed from Asia to North America in 

 the middle or late Tertiary, had there met and been adopted by the 

 Hylids and had been changed by their new hosts from broad to nar- 

 row form. Of course, some might claim that if the Hylids in North 

 America could change a broad Opalina into a narrow one, an emi- 

 grant Hyla in Euro- Asia could do the same thing. Such parallel 

 evolution, however, is not as probable as is the suggestion that the 

 emigrant Hyla carried its narrow Opalina with it from America. 



Note the extent of the spread of the Hylidae : From southeastern 

 Brazil to all tropical America, including Central America, the West 

 Indies, and the Bahamas; to all North America, and on by way of 

 Alaska to Siberia and China and across to Europe and northern 

 Africa ; also from tropical America to Australia. A wider spread- 

 ing would be possible only by adding the distance from southern 

 Brazil to Cape Horn and from Abyssinia to the Cape of Good Hope. 

 This wandering may mostly have occurred since the middle Pliocene 

 when the Isthmus of Panama was established, but of this we can not 

 be certain. Only the Bufonidae, among the Anura, have a wider 

 distribution. 



It is noteworthy that migration of Hylids from Central America 

 south Avard into South America apparently has not occurred, at least 

 not with any freedom, for if it had occurred in any abundance some 

 Hylids bearing species of the genus Opalina should be found in South 

 America, since half a dozen Central American species of Hylidae 

 carry Opalinae; but no Opalinae are known from South America 

 in these or any other hosts. 



To summarize: The family Hylidae seems to have arisen in the 

 southeastern Brazilian highlands, from forms related to the early 

 Bufonidae. They spread to Australia by a southern trans-Pacific 



