104 



INTRODUCTION 



as regards their degree of development in individuals 

 of the same species, and their arrangement also varies, 

 within certain limits, irrespective of the species. I 



Fig. 46. 



Tadpoles showing sensory canals. A. Rana agilis. b. Pelodytes 

 punctatus. c. Alytes obstetricans. (From ' P. Z. S.,' 1891.) 



have found them usually most distinct in Pelodi/tes, 

 Pelobates caltripes, Rana agilis, R. latastii, and Bom- 

 binator igneus ; least in Bufo. I append figures (Fig. 

 46) of tadpoles of Rana agilis, Pelodytes punctatus, 



