226 REPTILES AND BATRACHIANS 



or only slightly nicked. The tympanum is distinct or 

 hidden. The family is cosmopolitan, except for the 

 Ethiopian and the greater part of the Indian regions.. 

 Most of its members are small in size, although H. maxima 

 of British Guiana, and H. vasta, of Hayti, attain a length 

 of over five inches. 



The Common Tree-Frog, H. arhorea^ ranges from 

 Western Europe, North-West Africa, Madeira, and the 

 Canary Islands to China and Japan. This frog, which 

 attains a maximum length of not much more than two 

 inches, has the head much broader than long ; the snout is 

 short and rounded, and scarcely projecting. The tym- 

 panum is distinct. The fingers are webbed at the base, 

 the terminal discs equalling the tympanum in size. A 

 strong fold separates the hand from the forearm above. 

 The skin is perfectly smooth above, granular on the belly 

 and under the thighs. The male is distinguished by a 

 large external subgular vocal sac, which, when empty, 

 forms folds, but when blown out resembles a bladder, 

 and which is then considerably larger than the creature's 

 head. 



This frog, which is normally uniform bright green above, 

 has the power of not only changing colour, becoming at 

 times silvery white, yellow, or dark brown, but also of 

 putting on temporary light or dark spots. In the variety 

 japonica of Japan and China, however, dark spots on the 

 back and cross-bars on the limbs are always present. Bright 

 blue specimens are sometimes met with, due, as mentioned 

 when dealing with the aberration in the Edible Frog, to 

 the absence of yellow pigment. 



In Central Europe the breeding season extends from the 

 beginning of April to the middle of June, during which 



