118 ELEMENTS OF COMPARATIVE ZOO LOOT. 



F.O.SO.-Diagram of the stomach 



foot passing up between the middle toes; in other words, 

 they have cloven hoofs. In all other artiodactyls the cloven 

 hoof occurs, and besides, they chew the cud, and hence they 

 are associated as a group of ruminants. The stomach is 

 di rided into four chambers, and when a cow, for instance, 



feeds, it swallows the grass 

 without chewing it. It passes 

 down to the first stomach and 

 thence to the second. In these 

 it becomes mixed with digestive 

 fluids and softened. It is then 

 brought up into the mouth, 

 thoroughly chewed, and again 

 swallowed. This time it passes 



int the thM Sumach, and 



frOm this int the fourth > and 

 so into the intestine. 



To the ruminants belong the most valuable domesticated 

 animals. In South America are found the llamas and 

 alpacas, which were the cattle and beasts of burden of the 

 ancient Peruvians ; while in Asia and Africa the camels, in 

 part, take their place. Two kinds of camels occur, one 

 with one and the other with two humps upon the back. 

 These humps are merely large masses of fat. Some forty 

 years ago the United States Government introduced some 

 camels into our southwestern territory, and the descendants 

 of these are still to be found in Arizona. 



We associate together under the common name of deer 

 all those ruminants which have horns consisting of solid 

 bone. These horns are annually shed and grow out anew 

 each year, usually increasing in size with the age of the 

 animal. When first formed the horns are covered with a 

 thin skin with short hairs. The horns in this condition are 



