Order ARTIODACTYLA 197 



foot. The order includes the horse, tapir, and the rhinoceros, 

 each known from only a few species. There are no living native 

 North American representatives of the order in Illinois, but the 

 domestic horse, of Old World origin, is familiar to all. 



The horse is mentioned in this Fieldhook not because anyone 

 would have any difficulty in identifying the whole animal, but 

 because a collector might find a horse skull or tooth, which is 

 not readily identified. The skull and molar tooth of a horse are 

 illustrated in figs. 40/ and 109r, and identifying features are 

 given in the key to orders, beginning on page 41. 



ORDER ARTIODACTYLA 

 Even-Toed Hoofed Mammals 



Mammals of the order Artiodactyla have a large, hard hoof on 

 the third and another on the fourth toe of each foot, and the 

 principal support for the foot is shared by these two toes. The 

 result is the forming of the familiar so-called "cloven hoof." 

 The other toes may be represented by smaller hoofs or by 

 vestigial structures. The order is a large one, representatives 

 of which are distributed all over the world. It contains many 

 strange animals, such as the hippopotamus, camel, and giraffe. 

 North American representatives include members of the deer 

 (Cervidae), sheep and bovine (Bovidae), pronghorn (Antilocap- 

 ridae), and pig (Suidae) familes. 



When white men first arrived in the Illinois country, three 

 species of these artiodactyls occurred w r ild in the area — the 

 bison, the elk or wapiti, and the white-tailed deer. Land settle- 

 ment and intensive farming caused all three to disappear from 

 Illinois in the previous century, but in recent years the white- 

 tailed deer has been successfully reintroduced. This species is 

 the only wild representative of the order Artiodactyla in the 

 state. 



Several domestic animals belong to this order — the cow, sheep, 

 goat, and pig. These are well known, and no key is needed for 

 identification of the whole animal. There is a good possibility, 

 however, that if skulls of these animals, figs. 107a, 108<r, b, c, 

 are found they will be confused with deer, elk, or bison skulls 

 that may be unearthed. A key has been added for the identifi- 

 cation of these skulls. Some of the molar teeth of the cow are 

 illustrated in fig. 109a, b. 



