Hylidae 



change of dress when we have considered all gradations between 

 white and stone-grey or brown. There is almost as wide a range 

 between white and green. When the background of colour is 

 green, his characteristic markings may or may not appear. Also, 

 there may be various combinations of the green and the grey. 

 One of the most attractive of his suits is bright grey, with dark 

 grey markings broadly bordered with bright green. 



The underparts are light. There is much orange-yellow on 

 the body and legs where they fold against one another. This 

 colour is very conspicuous when the tree frog leaps. 



The changes in colour are not rapid, an hour at least seeming 

 necessary to create any radical difference. But it is usually true 

 that the given dress — whatever it may be — harmonizes so 

 perfectly with the surroundings — whatever they may be — 

 that the tree frog is as invisible as though he were Perseus in his 

 charmed helmet. Whether his resting-place be a green leaf or a 

 plant stem, the bark of a grey birch or a lichen-covered oak, (Figs. 

 134 to 137), his dress and his ability to keep perfectly still for 

 hours at a time form an excellent protection. Chance may bring 

 him to our hands many times in a summer, but he is very difficult 

 to fmd if we make definite search. 



In the difi'erent parts of its range, this Hyla shows considerable 

 variation. The variation displays itself mainly in the changed 



shapes of the dark markings of head and back 

 and in the varying amount of dark mottling on 

 the undersides of the legs. Cope describes 

 a brown spotted form from Mount Carmel, 

 Illinois, giving it the rank of a variety (Hyla 

 versicolor -phcEocrypla Cope). 



In May, when apple trees are loaded 

 with flowers and give out their delicate frag- 

 rance, and the low hum of honey-bees, we 

 may know that our tree frogs have put aside 

 their sleepy tendencies for the time and are 

 joyously paddling about in the water of some 

 pond. The painted-cup and golden ragwort are 

 giving colour to the marsh nearby. Probably 

 the jack-in-the-pulpit means only convenient 

 shade and a comfortable seat to the frogs. 

 (Frontispiece.) Very likely they do not even 



In May •when ap- 

 ple trees are in 

 bloom the Common 

 Tree Frog is at the 

 ponds. 



120 



