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 taurus. 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- 

 elude it with the cow in a genus called 

 2^os y calling the cow Bos taurus, and 



. , . , 



the blson > Bos blSOn - 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 ? 



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-horned animals. 



This family, because of its even number of toes and 

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



FIG. 8. Mucous MEM- 

 BRANE formed of one 

 layer of cells. A few 

 cells secrete mucus. 



