Ungulates 
peculiar four-parted stomach and the habit of casting up the 
hastily cropped grass for further mastication when resting later 
on. This operation is called ‘‘chewing the cud,” and one of the 
compartments of the stomach serves as 
a receptacle for the food, while it awaits 
this supplementary chewing. The canine 
teeth are often wanting in the hoofed 
animals and in the ruminant group the 
front teeth or incisors of the upper jaw 
are also lacking. The large grinders or 
molar teeth are always present and exhibit 
the most complicated type of tooth known. 
Most of the ruminants are further peculiar 
in the possession of horns or bony ant- 
lers growing out from the top of the 
skull. 
Great numbers of fossil ungulates 
have been discovered and it has been 
Foot of a ruminant (sheep) Possible to show the gradual evolution 
Be es aoe oectice of the living species through a_ long 
ee eee. Sapa cies of Sue Bus os. ‘ 
ponding toe Be Remains of extinct horses and _ rhi- 
noceroses have been found abundantly 
within the United States as well as animals for which we have 
no familiar names. To-day, however, our native ungulates are 
comparatively few in number and are grouped in four families, 
all of them belonging to the even-toed division. 

I. Peccaries (Family Dicotylide). Pig-like animals, not ruminant 
and without horns. Canine teeth large and prominent, 
front teeth (incisors) in both jaws. 
Il. Deer, elk, etc. (Family Cervid@). Ruminant animals with 
bony branching antlers on the head of the males (and 
females aiso in the caribou), which are shed every year. 
Rudimentary .canines generally present but front teeth 
(incisors) only in the lower jaw. 
lll. Prong horn (Family Antilocapride). Allied to the cattle 
(Bovide), but the hollow horns are forked and are shed 
as in the deer. 
IV. Cattle and their allies (Family Bovidw). Ruminant animals 
with hollow horns fitting over bony prominences on 
the skull in both males and females. These horns are 
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