TADPOLES. 107 



Tail not more than once and a half as lono- 

 as the body . . .P. cultripes. 



2. Spiraculum directed straight backwards, 

 tail rounded at the end ; both upper and 

 lower lip with toothed edge ; series of 

 labial teeth § . . . . Bdto. 



Mouth at least as wide as the interocular 

 space, which is twice as great as the 

 distance between the nostrils ; second 

 upper series of labial teeth very narrowly 

 interrupted in the middle . B. vulgaris. 



Mouth nearly as wide as the interocular space, 

 which measures once and a half the dis- 

 tance between the nostrils ; second upper 

 series of labial teeth more or less inter- 

 rupted in the middle . . B. viridis. 



Mouth considerably narrower than the inter- 

 ocular space, which is nearly twice as great 

 as the distance between the nostrils ; 

 second upper series of labial teeth very 

 widely interrupted in the middle. 



B. calamita. 

 b. Anus dextral ; spiraculum directed backwards 

 and upwards ; lower lip bordered with 

 papilla?. 



1. Anus opening above the lower edge of the 



tail ; upper caudal crest extending far 

 forwards on the back, almost to between 

 the eyes, which are lateral and visible 

 from the ventral as well as from the 

 dorsal aspect of the body ; series of labial 

 teeth § Hyla. 



2. Anus opening close to the lower edge of the 



tail ; upper caudal crest not extending 

 forwards beyond the vertical of the spira- 

 culum ; eyes on the upper surface. Rana. 

 a. Series of labial teeth —^-^-. 

 Interocular space at least twice the distance 

 between the nostrils, and much greater 



