20 THE BIOLOGY OF THE FROG CHAi. 



or brownish color above, marked only with small irregular 

 black spots. The dermal plicae are conspicuous. The hind 

 legs are short and the web extends well out on the toes. 

 The most conspicuous feature of this species is the very 

 large tympanum, which in the male considerably exceeds the 

 diameter of the eye. In the female the tympanum is con- 

 siderably smaller, being about three fourths the diameter of 

 the eye and " distant from the latter by nearly half its own 

 diameter." This species is widely distributed from the 

 Eastern States to Missouri and Minnesota and from Canada 

 to Florida and Mississippi. It is closely confined to water 

 like the bullfrog. It may reach a length of three inches. 



Rana sylvatica, the wood frog. — Unlike the two preced- 

 ing species, R. sylvatica is usually found in damp woods 

 often far from water. It occasionally occurs at a consider- 

 able elevation, one specimen having been taken by Mr. 

 Allen near the top of Mount Bartlett, New Hampshire, at 

 an altitude of twenty-five hundred feet. This frog, says Mr. 

 Allen, " is commonest in the beech woods and so closely 

 resembles in color the dead beech leaves, that not infre- 

 quently, even after having seen one jump, it is with diffi- 

 culty distinguished from the background. When frightened 

 it takes prodigious leaps in an erratic course, and usually 

 escapes into some hole or under a log. At night, while 

 walking in a damp spot in the woods, I found numbers of 

 them congregated in the path, where they had probably 

 come to feed. . . . Rarely have I heard them utter a 

 sound in the summer, though occasionally, when in the 

 woods at night, I have detected their faint, rasping ' craw- 

 aw-auk.' " 



Ranapipiens, the leopard frog. — This is perhaps the most 

 common of all the North American species of Rana. Its 

 ground color is green marked with rather large black 



