in GEOGRAPHICAL DISTRIBUTION 69 



but if there is sufficient mud, with decaying vegetable matter, the 

 creatures survive, simply because they are not absolutely frozen. 

 A severe winter not infrequently kills off all the younger 

 creatures, while the older and more experienced hide themselves 

 more carefully and live to propagate the race. 



Geographical Distribution. 



There is a very ably written chapter on the geographical 

 distribution of the Amphibia by Boulenger in the Catalogue of 

 Batracliia Gradientia, pp. 104-118. He came to the important 

 conclusion that the geographical distribution of the Amphibia 

 agrees in general with that of the freshwater fishes. Giinther's 

 division into a Northern, Equatorial, and Southern zone is 

 modified only in so far as the last two are combined into one, 

 " Tasmania and Patagonia not differing in any point regarding their 

 Frog Fauna from Australia and South America respectively." 



Boulenger recognises 



I. The Northern zone (1) Palaearctic, (2) North American, region. 

 II. The Equatorial Southern zone. 



A. Firmisternia division Cyprinoid division of Giinther. 



1. Indian region. 



2. African region. 



B. Arcifera division = Acyprinoid division of Giinther. 



1. Tropical American region. 



2. Australian region. 



In the chapter on geographical distribution in Bronn's Thierreich, 

 Vogel, Systematisclier Theil, p. 296 (1893), and in my Classifica- 

 tion of Vertebrata (1898), due attention had been paid to the 

 Amphibia as well as to the other classes of Vertebrata. It 

 will be seen in the following pages that my arrangement is well 

 applicable to the Amphibia so far as fundamental principles are 

 concerned. 



It cannot be sufficiently- emphasised that any attempt to form 

 the various faunas of the different classes of animals into one 

 scheme must necessarily be a petitio principii. The time- 

 honoured six zoo-geographical regions established by Sclater and 

 Wallace represent fairly well the main continental divisions : 

 North America, South America, Africa, Australia, and the large 

 northern continental mass of the Old World, with India as a 

 tropical appendix. There is no correlation and no subordination 



