202 , THE ANIMALS AND MAN 



States. The largest of these, and indeed the largest of all 

 the frogs, is the well-known bullfrog, which reaches a length 

 (head to the posterior end of the body) of eight inches. It 

 is found in ponds and sluggish streams all over the eastern 

 United States and in the Mississippi Valley. It is greenish 

 in color, with the head usually bright pale-green. Its croak- 

 ing is very deep and sonorous. The pickerel-frog, which is 



Fig. 99. The southwestern tree-frog, Hyla arenicolor. (After Dickinson.) 



bright brown on the back, with two rows of large, oblong, 

 square blotches of dark brown, is found in the mountains of 

 the eastern United States. The little, pale, reddish-brown 

 wood-frog, with arms and legs barred above, is common in 

 damp woods, and is "an almost silent frog." 



The true tree-frogs, or tree-toads, constitute a family 

 especially well represented in tropical America. They have 

 little pad-like swellings on the tips of their toes, to enable 

 them to hold firmly to the branches of the trees in which they 

 live. Some, like the swamp tree-frog and the cricket-frog, 

 are not arboreal in habit, remaining almost always on the 

 ground. The common tree-frog of the Eastern States is 

 green, gray, or brown above, with irregular dark blotches, 

 and yellow below. It croaks or trills, especially at evening 

 or in damp weather. Pickering's tree-frog makes the "first 

 note of spring" in the Eastern States. This is the one most 



