The Florida Tree Frog 



It has very rarely been found outside of Florida. It is the largest 

 tree frog of North America, and probably very valuable in the 

 work of destroying noxious insects. 



Hyla gratiosa presents a peculiar appearance because of the 

 even granulation of the upper parts. In this characteristic of 

 the skin it differs from all other North American Hylas. All 

 others present a surface either smooth and fine in texture, as in the 

 case of the Green Tree Frog (Hyla cinerea, Figs. 1 54 to 160), or one 

 rough with fine warts, as in the Common Tree Frog (Hyla versi- 

 color, Figs. 134 to 137). 



The Florida Tree Frog has colour changes as marvellous as 

 those possessed by most of the Hylas. It may be plain bright 

 green and remain so for months, in fact, one in this phase of col- 

 ouration was kept for over two years and during this time there 

 was no tendency to become spotted or to turn brown. Also, the 

 brown-spotted phase may likewise endure for months without 

 change. On the other hand, the changes may be very rapid 

 indeed. The tendency for rapid colour change, here as elsewhere 

 among the Hylidae, seems to be at its height when the animals 

 are well-fed, and in the season of greatest activity, that is, in the 

 spring and summer months. At this time the greatest variation 

 in colour may be seen in an individual during the twenty-four hours. 

 It may be bright green with vivid spots, dark at their edges and 

 light in their centres. Gradually (within the space of ten minutes) 

 the spots become more and more obscure until the frog is plain 

 green, very light in tone. Again, within the half-hour the spots 

 reappear, become more distinct, dai'cening in their centres. The 

 ground colour becomes ashy in the middle of the back; this colour 

 darkens into a mulberry, which colour spreads, obscuring the 

 green. Meanwhile the spots continue to darken until the whole 

 frog is rich brown prominently marked with darker brown spots. 



The throat-pouch of the male is very large and is bright yellow 

 or vivid green in colour. When the tree frog is taken suddenly 

 into the hand, this sac is likely to be inflated and the frog gives a 

 harsh-sounding squawk. The voice is unusually harsh and low- 

 pitched. 



This Hyla is a curiously artificial-looking frog. If it did not 

 move, we might well think some one's fancy had moulded it out 

 of wax. When it is angry or startled, it fills the lungs, expanding 

 the body until it is nearly as broad as long. It has the slow ten- 



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