Variation of the Kdibh Frocj. 255 



Einopeaii forms, the course I have followed is surely the 

 better irom a phiiosophicjil point of view, whilst the use of a 

 varietal designatiou [jrcchules all fear ot' the distinetion l)eing 

 overlooked. 



The followin<^- diagram expresses the relationship between 

 the live forms, as I eoiieeive them : — 



Var. lessonce. Var. chinensis. 



I 

 1'. ti/pica. , ^ 



Var. sdlnin'cn. I /^ 



Var. vulibunda. 



AVc cannot }et a})ply the test of crossing experiments 

 in justitieatiou of the subordinate position assigned to 

 7?. chinensis, as Ptluger was able to do in the case of 

 it!, escidenta and its var. ridibunda, but another ph^'siological 

 argument has been put forward by Wolterstorff : the large 

 and oiten sharp-edged metatarsal tubercle of it!, chinensis is 

 an adaptation to burrowing habits unlike those of li. escidenta. 

 We are told that Dr. Kreyenbe'g observed the Chinese frog 

 to dig and retire deep into the ground of dried-up rice-fields, 

 and this habit is regarded as an imj)ortant ethologieal 

 differentiation from its European representatives. Curiously, 

 however, Fejervary very shortly after redeseribed the var. 

 lessonce under the name of \av.balkai/i, from specimens living 

 in marshes at the mouth of the Rhone in Switzerland, and 

 observed the behaviour of this frog on land to be different 

 from that of the typical ii!. esculenta, the large and somewhat 

 movable metatarsal tubercle being used to burrow in the 

 ground after the manner of Pelobates. It is interestiiig to 

 note, in this connection, that Wolterstorff, who (1906) 

 seemeil to attach so great an importaiu^e to this peculiarity 

 in the case of the ('hmese frog, had (lUOJ:) only reluctantly 

 recognised is*, lessoncb's rank as a variety, a term which for 

 him expresses mere individual variations, such as his colour- 



simple variet6 de liana escidenta, L., a des cnracteres propres et con- 

 stants qui lui uieritent une description jiarticuliere et un uom special ; 

 elle nie !?emljle cependant assez voisiiie de liana esculenta pour que je 



crois utile de ne Ten point sdparer speciliquenient Et si, apies 



quelques hesitations, je me decide a cla.'^ser [it", chinensis] comma sous- 

 espece de li. esculenta, c'est par cette seule consideration qu'elle me 

 paiait beaucoiip plus voisine de cette dernitre que de toutes les autres 

 f^Teiiouilles." 



