II HABITS AND NATURAL HISTORY OF THE FROG 23 



CHAPTER II 

 THE HABITS AND NATURAL HISTORY OF THE FROG 



Habitat. — The habitat of Rana pipiens, Hke that of most 

 species of frogs, is usually in or near the water. In damp or 

 wet weather, however, this species frequently wanders for a 

 considerable distance from its aquatic home. It is liable to 

 be found almost anywhere near the shores of lakes, ponds, or 

 streams in the wide territory over which it is distributed. 

 Its range as given by Cope is from " Athabasca Lake, in the 

 north, to Guatemala inclusive, in the south," and from the 

 Atlantic coast to the Sierra Nevada Mountains. It has, 

 therefore, the widest distribution of any of the North Ameri- 

 can species of Amphibia, although it is not known to occur 

 on the Pacific slope. 



That Rana pipiens is confined to the neighborhood of 

 watqr depends in great measure on the fact that the skin 

 must be kept moist in order that cutaneous respiration may^ 

 take place. As soon as the integument becomes dry, as it 

 quickly does if the frog is exposed to a warm dry atmosphere, 

 it is no longer capable of serving as an organ o^ respiration, 

 and the animal soon perishes. The frog, unle>. it is among 

 wet grass or weeds, or in a moist atmosphere, must remain 

 where it can moisten the skin by an occasional plunge into 

 the water. Another circumstance which serves to keep the 

 frog in close proximity to water is the means thus afforded 

 of escaping from enemies. Any one who has walked along 

 the margin of a pond or stream must have observed that 



