TREE FROGS 



it to be. Under the skin of the back is a bony plate, 

 which is to be looked upon, as far as our present know- 

 ledge goes, as a relic of the largely developed skin 

 armature of some extinct forms of amphibians belonging 

 to the well-known Labyrinthodonts. The green colour 

 is quite an amphibian green ; it might be termed perhaps, 

 according to a classification of greens that we have 

 seen recently, neither light nor dark, but " pleasing." 

 Specimens have been on view at the Zoo at any rate 

 since the year 1859. 



A GREEN TREE FROG 



It is a common belief that all tree-frogs are green. 

 This is not the case ; some are mottled brown and of the 

 general Batrachian colour. But a good many are green ; 

 and, as is the case with green tree-snakes and green tree- 

 lizards, it is probable that they suck some profit there- 

 out. The invisibility, however, is due to colour and 

 not to form. Flat and adpressed to the leaf or stem 

 though the frog sits, it is said that a photograph at once 

 betrays its presence. Nature or a water-colour drawing 

 may be deceptive ; not so the camera. With the excep- 

 tion of three species, of which one, that concerning 

 which we shall have something to say here, is European 

 and Asiatic, the tree-frogs are confined to America and 

 to Australia. Since they are not always green, it be- 

 comes important to be able to say what a tree-frog is 

 by some other method than a mere inspection of colour. 

 The Hylidae, called after the youth beloved of the Naiads, 

 but who declined to dwell with them in fountains, 

 differ from most other frogs in the adhesive pads de- 

 veloped upon their fingers and toes which allow them 

 to sit tight upon smooth surfaces, and the existence of 

 teeth in the upper jaw. The former character alone 

 is not enough. The common tree-frog, Hyla arbor ea, 



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