I I.J THE COMMON FROG. 13 



wards this third finger barely attains (if it can do so 

 at all) the hinder end of the body. 



The hind limbs proceed from quite the hinder end 

 of the body, there being no vestige of a tail. The 

 thigh is very muscular, and the leg has a good "calf" 

 The foot is exceedingly long and, what is very re- 

 markable, is so jointed that the toes can be sharply 

 bent upwards on its thick and undivided part. The 

 latter thus seems to form a third segment of the hind 

 limb following the thigh and the leg, the limb having 

 thus four segments instead of three as in ourselves, 

 and in almost all beasts, birds, and reptiles. 



The foot ends in five toes connected by a web. Of 

 these the fourth is the longest, the first the shortest. 

 On the inner margin of the sole of the foot, at the 

 root of the first toe, is a small, hard prominence, 

 called a "tarsal tubercle." When the hind limb is 

 turned forward, the knee reaches nearly to the armpit ; 

 the ankle-joint is about on a line with the end of the 

 snout, and both parts of the foot are beyond it. These 

 two parts of the foot together are much longer than 

 the whole fore limb, and exceed two- thirds of the 

 length of the whole mass of the head and body. 



When the animal is viewed in profile, the point of 

 the muzzle is seen to be very little in advance of the 

 opening of the mouth. The latter is straight. It is 

 also very wide, extending back even beyond the 

 hinder margin of the eye. Just above the hinder 

 angle of the gape, and behind the eye, is a rounded 

 surface of smooth, tightly-stretched skin. This is 

 called the "tympanum," and directly covers in the 

 drum of the ear. 



