HERPETOLOGY OF THE GRAND DUCHY OF BADEN. 389 



pally with the striated variety. I have detected no traces of 

 green colour. It is worthy of note that the throat, generally pure 

 white or of a bluish tinge, is, with some females, spotted like the 

 lateral portions, and in the corresponding male form of a uniform 

 dark iron-grey ; in both cases with a white streak down the 

 centre. This detail becomes more significant when we encounter 

 an identical sexual difference with individuals of R. fusca. 



Turning to some points of biological interest, it has struck 

 me that the proportion of the sexes is more evenly balanced here 

 than with most batrachians. It seems remarkable that this 

 boreal species, which we should imagine to be less susceptible to 

 cold than R. fusca, should nevertheless spawn three or four weeks 

 later : it is as though this habit, necessitated formerly by a more 

 rigorous climate, had been permanently inculcated into the con- 

 stitution, and we are led to speculate in how far the advantages 

 conferred by such peculiarities — cf. R. ridibunda and Bombinator 

 bombinus — may have played a part in the gradual differentiation 

 of specific forms. But in the vast majority of cases it is vain to 

 decide the priority between change of habits and modification of 

 structure. 



R. arvalis emerges from its winter quarters at Eggenstein 

 towards the end of March. The spawn is not deposited till the be- 

 ginning of the following month, and then by no means always in 

 the water, but on comparatively dry land (hence distinguishable 

 by its small size from that of R. fusca) ; with the result that, if 

 there is a spell of three or four hot days during the season, great 

 quantities become dried up and wasted. The frogs themselves 

 suffer much from these temporary droughts : the males especially, 

 in their redundant condition, may be found in numbers lying 

 dead or dying on the ground. Whenever possible, they bury 

 themselves under tufts of grass so effectually that, before I was 

 aware of this habit, I imagined the entire colony had emigrated 

 to new pastures, leaving only the unburied dead behind them. 



Their aversion to remaining long in the water was also not 

 explained till, after capturing several injured specimens,* I 



* Mostly deficient in digits or entire limbs. The same applies to R. fusca 

 and Bufo vulgaris, which often exhibit curious malformations. The injured 

 part is but seldom renewed in its entirety, as with newts, but only replaced 

 by an indurated growth covering the exposed surface, or forming, in some 



