8 



ANIMAL BIOLOGY 



Method of Classifying Animals. The various animals 

 display differences more or less marked. The question 

 arises, are not some of them more closely related than 

 others ? We conclude that they are, since the differ- 

 ence between some animals is very slight, while the 

 difference between others is quite marked. 



To show the different steps in classi- 

 fying an animal, we will take an ex- 

 ample, the cow. Even little children 

 learn to recognize a cow, although indi- 

 vidual cows differ somewhat in form, 

 size, color, etc. The varieties of cows, 

 such as short-horn, Jersey, etc., all 

 form one species of animals, having the 

 scientific name tatirus. Let us include 

 in a larger group the animals closest 

 akin to a cow. We see a cat, a bison, 

 and a dog; rejecting the cat and the 

 dog, we see that the bison has horns, 

 hoofs, and other similarities. We in- 

 FIG. 8. MUCOUS MEM- elude it with the cow in a genus called 

 BRANE formed of one Bos, calling the cow Bos taurus, and 



layer of cells. A few . . , . , 



ceils secrete mucus. tne bison, Bos bison. The sacred cow 



of India (Bos indicus) is so like the 



cow and buffalo as also to belong in the genus Bos. Why 



is not the camel, which, like Bos bison, has a hump, placed 



in the genus Bos ? (Fig. 389.) 



The Old World buffaloes, most abundant in Africa 

 and India, the antelopes, sheep, goats, and several other 

 genera are placed with the genus Bos in a family called 

 the hollow horns. 



This family, because of its even number of toes and 

 the habit of chewing the cud, resembles the camel family, 



