PREFACE. 



Notwithstanding the great progress attained in our 

 knowledge of European Batracbians within the last 

 twenty years with regard to the distinction of species 

 and varieties, the study of their anatomy, life-histories, 

 and distribution, there exists at the present day no 

 work dealing with them as a whole from these different 

 aspects. 



For twenty-five years a close student and collector 

 of these animals, which have always exercised an 

 extraordinary fascination on my mind, I have often 

 wished for an opportunity of supplying such a de- 

 sideratum, by utilising the enormous material which 

 had gradually accumulated in the literature, my own 

 notes, and the unrivalled collection in the British 

 Museum. 



Thanks to the Council of the Ray Society, who, on 

 the special recommendation of Sir W. H. Flower, 

 acceded to my request, I have at last the satisfaction 

 of seeing my hopes realised, and, owing to the talent 

 of my artistic collaborators, Messrs. P. J. Smit and 

 J. Green, in a manner which fully satisfies my aspira- 

 tions. May those, few as they still are, who share 

 my fondness for this group of auimals endorse my 

 opinion of the beautiful and accurate illustrations 

 which are one of the principal features of this work, 



