294 



EANID.E. 



water. In Germany the larvae transform between 

 the middle of June and the beginning of August. 



In spite of what the great development of the meta- 

 tarsal tubercle would seem to indicate, this frog cannot 

 be said to show any special disposition to burrow ; and 

 as far as my experience goes, from having repeatedly 

 kept individuals in confinement, it does not seem in 

 any way to excel the common species in this respect. 

 The physiological significance of the character is no 

 more obvious here than in those varieties of Rana 

 esculenta in which the metatarsal tubercle attains so 

 great a development, without yet the frogs differing 

 appreciably in their mode of life from their spurless 

 allies. 



Fig. 106. 



~Sf 



Male and female pairing. 



Hybrids between this species and R. temporaria 

 have been obtained with great difficulty by Born, 

 the latter species acting as the male, whilst all 

 attempts at reciprocal crossing have hitherto failed. 



Eggs. — Intermediate in appearance between those of 

 R. esculenta and R. temporaria, the vitellus measuring 

 1^ to 2 mm. in diameter, and the mucilaginous envelop, 



