EeptiJes and Amphibians of Illinois. 345 



times sends distinct branches to the latter, and in some exam- 

 ples these seem to have become isolated and form dark spots 

 above the eyes. The stripe is often interrupted, and may be 

 continuous with one or other of the short stripes which begin 

 at its posterior end. The two latter may be united for a part 

 of their length across the middle line. 



With the first mild spring days, often before all the snow 

 and ice of winter have disappeared, the loud trill of this small 

 species may be heard from pools and ditches. The note is so 

 resonant that on quiet evenings it may be heard a half mile or 

 more and is commonly attiibuted to the larger frogs of 

 the genus Rana. When the note is uttered the vocal sac is 

 extended to its utmost and is larger than the head. Later 

 in the season the note is not heard and the species is not often 

 seen. It feeds upon insects. Hemiptera, Coleoptera, and in- 

 sects of other orders may be found in its stomach. 



Hyla, Laueenti. 



Laurenti, Synopsis Keptilium, 1768. 



Hoffmann, Bronn's Thier-Reich, VI., Amphibien, p. 6.53; Cope, 



ibid, p. 612 (quotation). 

 De Kay, Nat. Hist. N. Y., I., Zool. ill., Kept, and Amph., 1842, 



p. 71. 



Digits expanded into evident discs at their tips. Toes 

 webbed, fingers more or less webbed, or free. Tympanum dis- 

 tinct. Eustachian tube well developed. No parotid. Tongue 

 broad, entire or slightly excised, adherent, or more or less free 

 behind. Teeth present on upper jaw and on vomers. Skin 

 smooth or a little roughened. Sacral diapophysis widely ex- 

 panded. A fontanel between the fronto-parietals. Inferior 

 eyelid transparent. Males with one or two vocal sacs. 



This is a genus of arboreal frogs, the members of it 

 spending much of the time on trees and shrubs, to which they 

 cling by means of the large digital discs. They are very active, 

 leaping incredible distances when alarmed, but depending for 

 protection mainly on a ready power of suiting their color to the 

 surroundings. The species are most numerous in the neotropic 

 region. Twelve species occur in North America of which but 

 three have thus far been found in Illinois. 



