THE PROO. 53 



Description. 



THE FROG. 



THE color of the common frog is olive brown, 

 variegated above with irregular blackish spots. 

 Beneath each eye there is a patch or mark that 

 reaches to the setting on of the fore legs. Its 

 appearance is lively, and its form on the whole 

 by no means inelegant. The body is not covered 

 with either plates or scales, but is entirely naked. 

 It has a sternum or breast-plate, but no ribs, and 

 is also destitute of a tail. The limbs are well 

 calculated for aiding the peculiar motions of the 

 animal ; it has four feet, and its webbed hind 

 feet, which are longer than the others, assist its 

 progress in the water, to which it occasionally 

 retires during the heats of summer, and again in 

 the frosts of winter. During the latter period, 

 and till the return of warmer weather, it lies in 

 a state of torpor, either deeply plunged in the 

 soft mud at the bottom of stagnant waters, or in 

 the hollows beneath their banks. The mode of 

 respiration in these animals, in common with 

 many of the other reptiles, is exceedingly curious. 

 The organs adapted to this use are not placed in 

 the belly, nor in the lungs themselves, but in the 

 mouth. Behind the root of the tongue is the 

 slit-like opening of the trachea; and at the front 

 of the upper part of the head are two nostrils, 

 through which the animal always draws the air, 

 never opening its mouth for this purpose. Indeed 



