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PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 87 



genera of diverse character fitting their environment, more diverse 

 than in the rain forest. During the time when Patagonia, Antarctica, 

 and Australasia were connected, ZeZ^engZZa developed from Protoopalina 

 originally present, this evolution being probably rapid, so that the 

 leptodactylids carried Zelleriella wherever they spread, except for 

 Heleophryne in South Africa, perhaps not a leptodactylid. When 

 Patagonia became connected with tropical America, the leptodacty- 

 lids passed northward with their Zelleriellas. At about the middle 

 Pliocene the Isthmus of Panama was formed and leptodactylids and 

 Zelleriella passed on to Central America and to the Antilles, which 

 were then connected with Yucatan or Nicaragua or both. When 





FiGUKK 153.— Geographic distribution of the Lcptodactylidae. 



the leptodactylids reached Brazil they met Hylas and Bufos and gave 

 them Zelleriella, Hyla receiving these sparingly, Bufo with more 

 generous hospitality. The Australasian lands, after they were 

 stocked bj^ leptodactylids and Zelleriella, had no northern connections, 

 and even New Zealand was no longer connected, so that leptodactylids 

 and Zelleriella did not reach New Zealand, Malaysia, and Asia. 



Leptodactyhds have never been in Euro-Asia, for if they ever had 

 been and had become exterminated in some strange way (a wholly 

 improbable hypothesis) they would have given their Zelleriellas to at 

 least the Asian Bufos, a genus always hospitable to any genus of 

 opalinid. The leptodactylids and Zelleriella are of Antarctic origin, 

 using the word Antarctic to cover, not only the present, restricted 

 Antarctica, but the wider continent with its connected lands including 

 Australasia and Patagonia. Of direct connection between Antarctica 

 and South Africa the Opalinidae give us only little, if any, evidence. 



