330 BULLETIN 120, UNITED STATES NATIONAL MUSEUM. 



1 



cast doubt upon the idea of extensive intercontinental spreading of 

 Anura, and are inclined rather to believe, in some cases, that our 

 Anuran families and subfamilies are not formed in accordance with jlj 

 true genetic relationships, and that convergent independent evolution 

 accounts for the resemblance. Gadow (1909, p. 71) writes: 



It is one of the most difficult tasks to decide in cases of great resemblance of 

 groups of animals between their being due to direct affinity, or to heterogeneous 

 convergence, or parallel development. * * * the startling view that Mada- 

 gascar and South America have received part of their faunas from the famous 

 Antarctica. * * * The Dendrobatinae (Mantella in Madagascar, the others 

 in South America) are decidedly not a natural group, but an instance of very 

 recent convergence. 



Writing of the Pipidae, Gadow says (1909, p. 145) : 



We conclude now that all these four genera [Pipa, Xenopus, Hymenochirus, 

 and the European mid-Tertiary Palaeobatrachus] belong to one group with a 

 distribution formerly much wider than Africa and part of South America. 



ZellerieUa apparently definitely refutes the hypothesis of con- 

 vergence, so far as the Australian and South American Leptodac- 

 tylidae are concerned. It would perhaps be conceivable, though 

 difficult to believe, that the Australian Leptodactylids may 

 have evolved independently of the South American forms now 

 classed in this family. But it is hardly conceivable that almost 

 identical internal parasites were evolved also independently in the 

 two groups of hosts. ZellerieUa is a very compact genus morphologi- 

 cally, so compact that subdivision into valid species is difficult. The 

 Australian Z. hinucleata and some American Zelleriellas are espe- 

 cially similar. There seems_ no escape from the conclusion that the 

 Leptodactylids of America and Australia, and their parasites as 

 well, arose in some one region and spread to their present localities. 

 The evidence for an Antarctic land connection between South 

 America and Australia is greatly strengthened by the data ZellerieUa 

 and the Leptodactylidae present. Indeed the evidence seems con- 

 clusive. We should remember here the fact that Protoopalina 

 di'plocarya from Patagonia and P. acuta from Australia, both 

 parasitic in Leptodactylids, also P. papuensis from New Guinea, 

 parasitic in a Hyla, are forms very closely related to one another. 

 The Leptodactylidae are developed in greatest variety and number 

 in South America and probably arose in Patagonia or lands con- 

 nected with Patagonia. Their ZellerieUa parasites apparently arose 

 in the same region, being derived from the Protoopalinas by the 

 flattening of the body. Protoopalina xyster of Central America is 

 a partially flattened form which suggests the sort of intermediate 

 stage through which the ancestors of the Zelleriellas may have passed. 



The same line of reasoning does not hold as to Bufo and ZellerieUa 

 and a land connection between South America and Asia, for the re- 



