436 PRACTICAL ZOOLOGY 



These animals are characterized by the presence of an even num- 

 her of hoofed toes. 



The term ruminant has been given to the animals belonging 

 to the camel, deer, giraffe, and ox families, since they ruminate 

 or chew their cud. The food of these animals is swallowed with- 

 out sufficient mastication ; it is later regurgitated in small quan- 

 tities and thoroughly chewed. This method of feeding enables 

 " these comparatively defenseless animals to gather nutriment 



e ' 



FiG. 304. Stomach of a ruminant opened to show internal structure. 



a, oesophagus; b, rumen; c, reticulum; d, psalterium; e, abomasum; 

 f, duodenum. (From Flower and Lydekker.) 



in a short time and then retreat to a safe place to prepare it for 

 digestion." A typical ruminant possesses a stomach consisting 

 of four chambers (Fig. 304). The food is first taken into the 

 rumen chamber (b), where it is moistened and softened ; it passes 

 back into the mouth as " cuds " and is ground up by the molar 

 teeth and mixed with saliva. When the cuds are swallowed, 

 they are received by a second chamber (c), then pass into a third 

 chamber (d), and finally into the fourth chamber (e). 



The deer constitute the majority of the American hoofed 

 mammals. Their horns or antlers are solid, and are shed annu- 

 ally. The best-known species are the wapiti or elk and Virginia 

 deer, with round horns, and the caribou and moose, with flat 

 horns. 



