INTRODUCTION. 



probably expecting to find in it the rutieta of older writers, adds 

 that it ' ist fur giftig zu halten/ 



Leeuwenhoek T also, correctly distinguished between them, but it 

 is to Rosel 2 that we are chiefly indebted for a careful discrimination 

 a,nd an accurate knowledge of the life-histories of the two species. 



Fig. i. 



The green water-frog, Rana csculenta, L. 



Rana esculenta, L. The green water-frog, Fig. i, usually attains 

 a larger size 3 and is more active than the other species, and for this 



1 Leeuwenhoek, Arcana Naturae, Vol. Ill of Ecker's edition. Leyden, 1722. Epist. 65 

 ad Keg. Soc. Lond., p. 154. 



2 Rosel, Naturgeschichte derFrosche Deutschlands, ed. Schreber. Nurnberg, 1815, 



P- 36. 



3 The extreme sizes are much more pronounced in this species. I have never found 

 H. temporaria of the size attained by large specimens of the water-frog. 



