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we thus consider to have started as early as the Cretaceous period and 

 to have been completed before, in the early Tertiary union of the 

 Pacific land-strip with the North American Continent occurred. 

 (3) The Liopelminae spread southeastward across Malaysia, through 

 Australia, to New Zealand. This wandering occurred before AustraUa 

 and New Zealand separated from Malaysia and Asia, in other words, 

 apparently in Jurassic times (fig. 142, b). Liopelma, another decadent 

 genus, has completely lost its aquatic larvae and so has no opaHnids. 



¥ /K>' c^^ 



Figure ISO.— Geographic distribution of the Pelobatidae. 



But its ancestors, in passing across Australia, left their Protoopahnas 

 of subgenus II, and these are found there today resident in Hyla. 

 There is a further point of considerable interest. Hyla came to 

 Australia from South America and at a time later than the separation 

 of Australia from Malaysia, for Hyla is unknown from Malaysia. 

 It seems Hkely that the ancestors of Liopelma persisted in AustraUa 

 long enough to meet and infect Hyla, though the infection might have 

 been from Liopelma through a primitive bufonid or a leptodactyUd (?) 

 to Hyla} The point of interest is that discoglossid Protoopalinas are k 

 still in Austraha, though the discoglossids themselves are gone. I 



Discoglossids have come into contact with Cepedea but have not 

 adopted it. Similarly they have been in contact with Opalina, but 

 only in two or tliree instances have individuals infected with Opalina 

 been reported (from Europe), probably temporary infections. Disco- 

 glossids have not been in contact with Zelleriella. 



« ]t is not likely that the Hylidae and the Leptodactylidae entered Australia together, coming from Ant- ■ 



arctica. The Hylidae may have taken a more northern trans-Pacific route from tropical South America. I 



In this case the migration was probably earlier (late Cretaceous or, say, Eocene; flg. 144, a) than that of the 1 

 leptodactylids (Tertiary; fig. 144, 6). See p. 698. 



