FISHES, BATRACHIANS. AND REPTILES 217 



hatched. They conceal themselves by day, but will 

 appear after a warm shower ; this sudden appearance of 

 many small toads sometimes gives rise to the false notion 

 that they have fallen with the rain. 



There are about a dozen species of frogs in the United 

 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 croaking is very deep and sono- 

 rous. The pickerel-frog, which is 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 peculiar frogs, 

 infrequently seen, known as the "spade-foots," are 

 subterranean in habit, and usually live in dry fields, or 

 even arid plains and deserts. They pass through their 

 development and metamorphosis very rapidly, appearing 

 immediately after a rain, and laying their eggs in tempo- 

 rary pools. At this time they utter extraordinarily loud 

 and strange cries. Some frogs, in other parts of the 

 world, live in trees, and the eggs of one species are 

 deposited on the leaves of the trees, leaves which over- 

 hang the water being selected, so that the issuing young 

 may drop into it. 



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

 especially well represented in tropical America. They 

 have little disk- or 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. 



