I THE AMPHIBIA IN GENERAL 17 



Mexico and Texas fall into three genera. These are sepa- 

 rated by Jordan by the following key : — 



A. Disks small. Fingers not webbed. Palustrine. 



B. Toes broadly webbed. Tympanum indistinct . Acris. 



BB. Toes scarcely webbed. Tympanum distinct . Chorophilus. 

 AA. Disks round, conspicuous. Fingers somewhat 



webbed. Skin roughened. Arboreal . . Hyla. 



Acris is represented by a single species, A. gryllus, the 

 common " cricket frog," which is distributed over the greater 

 part of the United States. Its typical color is brown or gray 

 above, with a dark triangular patch between the eyes, with 

 the middle of back and head bright green or reddish brown. 

 There are variations in color in the specimens of different 

 regions and a considerable power of color change in the 

 individuals themselves. This species is usually found along 

 the banks of ponds and swamps. Its note resembles that 

 of a cricket. 



Hyla is represented by over a hundred species, ten of 

 which occur in North America. The species are mainly 

 found in trees. H. versicolor, so-called on account of its 

 remarkable change in color, is one of the most common and 

 largest of the North American species, reaching a length of 

 two inches. The eggs of this species are deposited singly 

 or in small clusters on grass growing near the water's edge. 

 The breeding period in Massachusetts, according to Miss 

 Hinkley, is in the early part of May. 



Many of the Hylidse possess singular devices for carrying 

 the eggs. In Hyla goeldii of Brazil the eggs are carried on 

 the back of the female, the skin being produced into a fold 

 which borders the egg mass. Nototrema, the " marsupial 

 frog" of South America, has a large pouch opening near the 

 posterior end of the back, in which the eggs are received, 

 c 



