Dr. A. Giinther on the Geographical Distribution of Reptiles. 317 



peculiar tree-frogs with a pouch on the back for their progeny ; and 

 there also we meet with the single representative of the Proteroylossa. 

 This region is the most productive in Batrachians, as we find the 

 East Indies to be in Snakes. At least 1 10 species are known, giving 

 one species for every oU.OOO square miles, rather more than one- 

 half of them belonging to the Platy dactyl a. South America pro- 

 duces one peculiar form of the Batrachians without tongue, Pipa — 

 the more characteristic of this region, as it is, moreover, provided 

 with pouches on the back, which are never met with in animals of any 

 other part of the earth. If such a Batrachian were found in Au- 

 stralia (as I think will be realized), it would aiford a strange point 

 of analogy with the distribution of the Marsupial Mammals. 



We find in several families genera which are distinguished by pe- 

 culiar development in the structure of certain bones of the skeleton, 

 especially of the bones of the skull : Cahjptocephalus, Ceratophrys, 

 Cystiynathus, Brackycephalus, Otilophus, Opisthodelphys, Trachy- 

 cephalus. Numerous are those forms of Oxydactyla as well as of 

 Platydactyla which have no web between the toes, and which are 

 in general peculiar to tropical regions. Two-thirds of the species of 

 Ryla are found in Tropical America. 



The genus Cystiynathus, which I have mentioned as common to 

 several regions, has most of its species in South America. Tschudi 

 has separated a part of it by the name of Pleurodema, containing 

 only South American species ; 1 have done the same, uniting moreover 

 a part of the Australian species under the name of Limnodynastes, 

 whilst the other part, I find, has received a third generic name. 

 But there remain still for Cystiynathus South American and iEthio- 

 pian species ; and these in fact, together with the separated species, 

 form a very natural group — genus or family — which is spread over 

 the Tropics, but not met with in the East Indies. If, on review, 

 we ask to which of the other Tropical regions the Batrachio- 

 fauna of South America is the most closely allied, we find that re- 

 gion to be Australia. Both regions agree in producing severally one- 

 Batrachian without tongue, and in producing CystiynathidcB, Hy- 

 lidw, and Hylina with paratoids, which forms are all wanting in the 

 East Indies ; they also agree in the absence of the large genus Rana, 

 and of the Polypedatidce* . On the other hand, there is hardly one 

 point of view in which we could find a relation between the Au- 

 stralian and East Indian regions ; and thus the fact appears to be 

 estabhshed, that Australia offers far more similarity, in its Batra- 

 chio-fauna to S. America than it does to the East Indies, on the 

 western coasts as well as on the eastern, and also that the real in- 

 tensity of species corresponds more with that in South America. 



The West Indies exhibit a Batrachio-fauna the character of which 

 quite agrees with that of S. America : there is, however, a greater 

 distinction of the species, a few only being identical with those of the 

 continent ; and the genus Hylodes may be considered as nearly pecu- 

 liar to these islands. 



I now give a Schema similar to that for the Ophidians, 



* There is in each region a single species ; in South America Elosia, in New 

 Guinea Cornufer unicolor. 



