AMPHIBIANS 



Fig. 284. — Tadpole (A) and young frog (B) with 

 their body walls spread open, showing the long 

 watch-spring intestine of the herbivorous tadpole 

 and the short food canal of the frog, which has be- 

 come carnivorous. 



Breeding habits. — The sexes are easily distinguished, 

 especially during the breeding season. Male frogs have 

 swollen thumbs (Fig. 285) or thumb-pads while the females 



\lj 



1 a. 3 



Fig. 285. — Right front foot of frog showing shape 

 of the thumb in different sexes: i, male with swollen 

 thumb, in the breeding season; 2, male with thumb 

 of smaller size as it is out of the breeding season; 3, 

 female. 



have more slender ones; in male toads the upper surfaces of 

 the thumb and first finger are rough and horny. In male 



349 



