VI 



HYLIDAE . 191 



Several ^•al•ieties have been descril)e(l : the typical or European 

 fonn is ornaiuented with a narrow black stripe, which, beginning 

 at the nose, extends backwards along the side of the l)ody to the 

 groin, where it generally forms a hook turned upwards. This 

 black colour forms the ^•entral boundary of the green, and is 

 itself narrowly seamed with white on its upper border. 



In the south of France, the Iberian Peninsula, Morocco, and 

 the Canary Islands the black lateral stripe is often absent ; 

 this is is the var. meridionalis. In Spain and Portugal both 

 forms are found in the same localities. 



In the Asiatic, chiefly in the eastern specimens, the lateral 

 stripes, tend to break up into irregular spots, vanishing altogether 

 towards the groins ; this var. savignyi s. japonica occurs also on 

 most of the Mediterranean islands. , 



IT. arborea can change colour to a great extent, mosth' in 

 adaptation to its immediate surroundings, but ill health and 

 moulting may also influence it. The change is slow. The usual 

 colour is green, brightest on bright, sunny hot days, dull when 

 the sky is overcast, or when it is w^ndy and showery. Day and 

 night have no influence upon the colour-changes. The hue of 

 the green agrees mostly with that of the foliage on which the 

 frog happens to take its rest, for instance a field of Indian corn, 

 birch-trees, or oak-trees. I once received a consignment from 

 Saxony. When the box with moss was unpacked, they were of 

 the dullest greenish-grey ; they were put into a wired-off corner 

 of the yard and were given the freshly cut branches of a lime-tree 

 to sit upon. On the following morning I at first looked for 

 most of the frogs in vain. The leaves had withered and all those 

 frogs which sat upon the dark brown branches had put on a light 

 brown garb, mottled with darker patches. 



Another specimen, one of several which were at liberty in 

 a greenhouse, took to resting on the frame of the window-pane, 

 in a corner where putty, glass, and discoloured white paint met ; 

 in the morning it was always of a mottled leaden colour, but 

 during the nocturnal hunting it was green. In the winter, the 

 windows-corner being of course cold, the frog remained stationary 

 for several months, but kept the leaden grey colour, until one 

 day in the early spring it was mottled with green, and soon after 

 it joined its green mates. 



Liebe observed a half grown tree-frog which he kept in Gera 



