Page:First course in biology (IA firstcourseinbio00bailrich).pdf/453

 because of the friendly custom cows have of combing each other's hair with their rough tongues, the hair sometimes being swallowed. Explain the saying that if a cow stops chewing the cud she will die.

(Camelus dromedarius).

Does a cow's lower jaw move sidewise or back and forth? Do the ridges on the molars run sidewise or lengthwise? Is a cow's horn hollow? Does it have a bony core? (Fig. 344.)

(Antelocarpa Americana). Western states.

The permanent hollow horns of the cow and the solid deciduous horns of the deer are typical of the two kinds of horns possessed by ruminants. The prong-horned antelope (Fig. 391) of