338 



LOWER VERTEBRATES. 



The Mexican Hyla arenicolor is said to utter a cry much like the bleating of goats. 

 The voice of the H.faber of Brazil is loud and metallic, resembling strokes on an 

 anvil. The noises of the Brazilian forest at nightfall are largely due to the species 

 of Hylidse that inhabit that country. 



The colors of the Hylidte are often brilliant, and are generally changeable in accord- 

 ance with the surfaces on which the animal rests. The Hyla versicolor presents a 



Fio. 202.— Si/la palmata, from Brazil. 



marked instance of metachrosis or color-change. When on the trunk of a tree, it may 

 be a dark brown, resembling the bark, or a very pale gray, representing a lichen. 

 When placed among leaves it becomes a bright green. The species of Acris and 

 Chorophilus can undergo similar changes. An Acris crepitans may be studded with 

 brilliant green spots, or have a green dorsal band, or it may be uniform dusky, or 

 have a rufous dorsal band. The species which live among foliage and flowers are 

 often brilliant in their hues. Thus Hyla pulchrilineata of San Domingo is green 



