14 THE COMMON FROG. [chap 



When the mouth is opened, if the finger be drawn 

 along the inner margin of the upper jaw, a series of 

 minute teeth may be detected. Towards the front of 

 the palate are a pair of small holes (which are the 

 inner openings of the nostrils), and between these are 

 two juxtaposed little groups of other minute teeth. 

 There are no teeth whatever in the lower jaw. At 

 the hinder end of each side of the palate is another 

 small hole. These latter two apertures are each the 

 opening of a canal leading from the mouth to the 

 cavity of the car within the drum. The tongue is seen 

 to be large, flat, and fleshy. It is tied down to the jaw 

 in front, but free for more than its hinder half, with 

 two processes developed from its free hinder margin. 



The skin of the Frog is naked and smooth, without 

 a trace of scales, or other appendages. Its colour on 

 the upper surface is more or less yellowish, or reddish 

 brown, with irregular black, brown, or grey patches. 

 Similar patches form transverse bands upon the legs. 

 Beneath, the colour is pale yellowish, often with a few 

 spots, paler than those of the back. There is con- 

 stantly a brownish black subtriangular patch placed 

 behind the eye, and extending over the tympanum 

 down towards the shoulder. The Frog breathes partly 

 by swallowing air (aided by a mechanism to be de- 

 scribed hereafter), partly by the direct respiratory 

 action of the skin. It feeds exclusively upon living 

 animals, such as insects and slugs, which it catches by 

 suddenly throwing forwards beyond the mouth, the 

 free hinder half of the tongue (furnished with an 

 adhesive secretion), ^nd then retracting it with its 

 prey in a most rapid manner. 



