ORDER UNGULATA. 



HOOFED MAMMALS. 



This order comprises the Hoofed Mammals, such as Deer, Oxen, 

 Horses, Sheep, Swine, Elephants, etc.,* representatives of the various 

 families being widely distributed throughout the world, except in 

 Australia and Madagascar. They are terrestrial, digitigrade, and vege- 

 tarian. The molars are broad, with ridged or tuberculate surfaces; 

 the teeth are heterodont or diphyodont; and the "milk teeth" remain 

 longer than in most mammals; clavicles are not present in living 

 species; the digits vary from one to five, and are usually incased in a 

 horny hoof, although in some cases, such as* the Elephants, there are 

 broad blunt nails. 



The American Ungulates belong to two suborders: Perissodactyla, 

 those having an uneven number of toes, such as the Horse and Tapir; 

 and Artiodactyla, those possessing an even number of toes, such as 

 Deer, Oxen, Sheep, etc. The latter are characterized by the prom- 

 inence of the third and fourth digits, while the second and fifth are 

 indicated by small lateral hoofs, or "false hoofs," which are rarely, if 

 ever, functional, and in some species are entirely absent. 



The suborder Artiodactyla is generally divided into two groups or 

 divisions consisting of (i) the Suinea, comprising the families contain- 

 ing the Swine and Hippopottami; 

 and (2) the Selenodontia, or Rum- 

 inantia,f comprising the other rep- 

 resentatives of the suborder, such as 

 Deer, Oxen, Sheep, etc., which rum- 

 inate or "chew their cud." 



In all "ruminants" the stomach 



Stomach of Ruminant j s usua lly divided into foUT COm- 



o, (Esophagus; b, rumen or pouch; h, reticu- * 



lum or honeycomb bag ; d, psalterium or manyplies; partmentS (in the Tragulid(B there 

 c, abomasum or reed; f, duodenum. (After " 



are but three), and the operation 



consists of forcing back the hastily and improperly chewed grass or 

 vegetable matter from the stomach into the mouth, where the food is 



* See page 28. 



t The Ruminantia are again subdivided into somewhat natural groups: (i) 

 Tragulina, comprising the Cheyrotains or Deerlets; (2) Tylopoda, Camels, Llamas, 

 Vicunas, etc.; and (3) Pecora, including the families Cermdce, Deer, etc.; Giraffida, 

 Giraffes and Okapi; and Bovidce, Oxen, Sheep, Goats, Old World Antelopes and not 

 unlikely the American Antelope or Pronghorn, although the last is usually placed 

 in a family by itself (A ntilocaprida) . 



57 



