POULTRY 463 



carnage horse has smaller hoofs, is long legged, and has a less 

 stocky body. The average horse is the intermediate between 

 these and is able to do moderately heavy work and at the 

 same time serve as a carriage horse. 



The cow, the sheep, the pig, and the horse belong to a group 

 of animals called mammals. They bear their young alive and 

 nurse them. Cats, 

 dogs, and rabbits also 

 belong in this group. 

 Mammals have either 

 a short, thick, hairy 

 covering like the 

 horse and the cow, 

 a fine inconspicuous, 

 hairy covering like 

 man, or a short thick 

 fur like the sheep or 

 the rabbit (Fig. 331). FlG 33I ._ A rabbit. 



Among mammals 



are found some harmful animals. The house rat, for ex- 

 ample, is known throughout the world as a pest to farm, 

 factory, ship, and house. Rats not only destroy good food, 

 but they also injure buildings and furniture by their gnawing, 

 and, what !S worse, they spread disease. The frightful 

 bubonic plague is spread by rats and a bonus is placed on 

 dead or living rats in infected cities. Field mice are a pest 

 to the farmer, undermining his fields and destroying his crops 

 (Fig. 332). 



Poultry. Chickens are greatly in demand for meat, but 

 their chief value is in the eggs which they lay. About twelve 

 billion eggs are used in the United States yearly. Even then 

 the demand is far greater than the supply. Eggs are nutri- 

 tious, easily digested, and usable in innumerable ways, and 



