82 BOLKAY 



ridibunda, but on the contrary both R. esculenta and R. ridibunda 

 from Rana chinensis. 



I wish to support this supposition by the inner meta-tarsal tubercle. 

 As is already known the inner meta-tarsal tubercle of frogs has de- 

 veloped from the ancestral thumb, the former sixth toe. If during 

 the development of the body any part of it is arrested in its growth 

 and decays, it regenerates no more. This is the fact on which I 

 found my explanation. In the above description I have already 

 pointed out the fact that the meta-tarsal tubercle of the Chinese 

 frog is truly no meta-tarsal tubercle at all, but a real finger connected 

 by a web to the present thumb. The Chinese frog, influenced by 

 surroundings and climatic conditions, adapted itself to the already 

 mentioned peculiar mode of life and its ancestral thumb just only 

 transformed itself so far as to become its burrowing implement. 



In opposition to this it is quite evident that the meta-tarsal tu- 

 bercle of Rana ridibunda and Rana esculenta has quite degenerated 

 inasmuch as through adaptation to new conditions, it increases its 

 dexterity in leaping. On account of this, therefore, it would be 

 impossible to suppose that the Chinese frog's meta-tarsal tubercle 

 together with the web between it and the first toe is a new acqui- 

 sition. 



I found on Bufo viridis Laur. a most convincing proof of the 

 change in the hind limbs caused by wandering. In one of my 

 articles (p. 166) whilst comparing the Bufo viridis of county 

 Gomor (Hungary) to Bufo viridis of Konia (Asia Minor) I pointed 

 out the fact of the specimens from Asia Minor having comparatively 

 a good deal longer hind limbs than those from the county Gomor. 

 After the publication of that article my friend Mr. D. v. Foldvary 

 who undertook a journey in Asia Minor in the year 1906, informed 

 me having repeatedly met in the deserts with Bufo viridis, wander- 

 ing in search of new pools after their former resorts had dried up. 



It seems likely therefore, that the hind limbs of the specimens 

 from Asia Minor were thus developed in consequence of this fre- 

 quent wandering, and it is to be presumed that Hungarian speci- 

 mens have shorter hind limbs, because they never wander. Taking 

 these above facts into consideration it will seem more probable still 

 that Rana ridibunda and Rana esculenta were derived from the 

 Chinese frog whilst this latter was extending westwards; the in- 



