XIII. 



THE FROG (Rana temporaria and Rana esculenta). 



THE only species of Frog indigenous in Britain is that termed 

 the ' common ' or ' Grass Frog ' (Rana temporaria), while, on 

 the Continent, there is, in addition to this, another no less 

 abundant species, the hind-limbs of which are considered a 

 delicacy, whence it has received the name of the 'Edible 

 Frog' (Rana esculenta). Unless the contrary be expressly 

 stated, the description here given applies to both species. 

 The Edible Frog is usually larger than the other, and is 

 therefore more convenient for most anatomical and physiolo- 

 gical purposes. 



In the body of the Frog the head and trunk are readily 

 distinguishable ; but there is no tail and no neck, the con- 

 tours of the head passing gradually into those of the body, 

 and the fore-limbs being situated immediately behind the 

 head. There are two pairs of limbs, one anterior and one 

 posterior. The whole body is invested by a smooth moist 

 integument, on which neither hairs, scales, nor other forms of 

 exosJceleton are visible ; but hard parts, which constitute the 

 endoskeleton, may readily be felt through the integument 

 in the head, trunk and limbs. 



The yellowish ground-colour of the skin is diversified by 

 patches of a more or less intense black, brown, greenish, or 

 reddish-yellow colour, and, in the Grass Frog, there is a 

 large, deep brown or black patch on each side of the head, 



