218 



BRANCH VERTEBRATA. 



FIG. 378. 



and passes directly into the fourth stomach, where the 

 actual process of digestion is carried on. The mechanism 



for conveying the un- 

 chewed mass in the first 

 stomach back into the 

 mouth also depends up- 

 on the lip-like tube. The 

 contraction of the walls 

 of the rumen forces por- 

 tions of the food into 

 the reticulum ; in turn, 

 the contraction of its 

 walls crowds a part against the outside of the lips, which, 

 opening, pinch off a portion, and, compressing it into a 

 ball, present it to the oesophagus, the fibers of which, 

 contracting successively from below upward, push it for- 

 ward into the mouth 



Skeleton of a Camel. 



FIG. 379. 



FIG. 380. 



Foot of a Camel. 



Water-cells of Camel's Stomach. 



Each foot of the Camel is provided with two toes, 

 united nearly to the point by a callous sole. In drinking, 

 water passes directly to the second stomach, which, on 



