CLASS AMPHIBIA 519 



eastern North America belong to the species Scaphiopus hol- 

 brookii. They are seldom seen or heard except during the breed- 

 ing season, when they come out of their burrows in great numbers 

 and seek ponds in which to deposit their eggs. 



Family 2. BUFONID^E. This family includes over one 

 hundred species of toads, most of 'which belong to the genus 

 Bufo. About fifteen species of this genus have been reported 

 from North America. 



Bufo americanus, the common toad of the northeastern 

 United States, possesses a rough, warty skin, but does not cause 

 the appearance of warts upon the hands of those who handle 

 it, as is often supposed. Toads secrete a milky, poisonous fluid 

 by means of glands in the skin, which protects them from many 

 animals that would otherwise be important enemies. During 

 the day they remain concealed in some dark, damp place, but 

 at night they sally forth and hop about, feeding upon worms, 

 snails, and especially insects, which they capture with their sticky 

 tongue, as in the case of the frog (p. 480, Fig. 410). The value 

 of toads as destroyers of insects injurious to vegetation is con- 

 siderable. Kirkland has estimated that one toad is worth 

 $19.44 in a single season because of the cutworms it devours. 



During the winter toads hibernate in some sheltered nook, 

 but as soon as conditions are favorable in the spring (about 

 May i) they emerge from their winter's home and proceed to 

 water to deposit their eggs. At this time the males utter their 

 sweet, tremulous calls. The eggs are laid in long strings. They 

 develop very much like those of the frog (pp. 506-510). 



Family 3. HYLID.E. The tree-frogs are arboreal amphib- 

 ians with adhesive discs on their toes and fingers which usually 

 enable them to climb trees. They are provided with large vocal 

 sacs and have a correspondingly loud voice. Of the more than 

 one hundred and eighty species belonging to the family, fifteen 

 occur in North America, and about one hundred and thirty in 

 Central and South America. The North American species 

 belong to the genera Hyla, Acris, Chorophilis, and Smilisca. 



