182 



Descriptive Zoology. 



food by means of the tongue. The tongue is attached 

 in front and free behind. Insects are caught by turning 

 the tongue forward quickly, the sticky mucus with which 

 the tongue is covered holding them securely. There are 

 fine teeth on the upper jaw and the roof of the mouth, but 

 these serve merely to hold the insect or slimy worm, while 

 it is being swallowed, and are not used for masticating the 

 food. The wide mouth narrows into the gullet, which is 

 really wide, since the animals captured are swallowed 



FIG. 116. PLAN OF FROG'S STRUCTURE, SIDE VIEW. 



whole, but is kept closed by being " puckered up," as it 

 were. Back of the gullet is the rather large stomach. 

 The stomach narrows as it extends backwards, and is con- 

 tinued into the intestine, which, after one or two turns, 

 suddenly widens into the cloaca. Alongside the stomach 

 is the lobed liver ; between two of the lobes is the bile 

 sac, whose duct empties into the intestine a short distance 

 behind the stomach. The duct from the small pancreas joins 

 the bile duct a little before the latter enters the intestine. 



