INTEODUOTION. 



fV OOLOGY (zoon, animal ; %os, a discourse) treats of animals. 

 / J It includes every variety, from man to the tiniest micro- 

 scopic creature. Recent investigations in Comparative Anatomy 

 seem to indicate that all the varied forms of life so shade into 

 one another as to furnish no sharply-marked dividing lines : and 

 that could the animals which have become extinct be grouped 

 with those now living, the entire series from man to the animal- 

 cule would present an unbroken succession. This panoramic view 

 would give an idea of unity in the same sense as when we speak 

 of a herd of cattle, though the individuals differ in size, color, and 

 form ; or of a landscape, in which there is no break in the undu- 

 lating outline of the far-off horizon, though it include river, 

 mountain, and valley. 



Classification. In order to understand Zoology clearly, it 

 is necessary to separate this vast ANIMAL KING-DOM, as 

 it is called, into different groups. If we examine the general 

 structure of the various animals, and bring together those which 

 have similar peculiarities as, for instance, a back-bone we shall 

 form the first grand divisions, which are styled SUBKING- 

 1) QMS. There are only six of these typical ideas; each, however, 

 developed by the all-wise Creator in wonderful diversity. 



Observing the characteristics of the animals composing a sub- 

 kingdom, particularly with regard to their physiological distinc- 

 tions as, for instance, whether they are covered with hair or 

 feathers we reach the divisions of each subkingdom, which we 

 designate as CLASSES. 



Observing the characteristics of the individuals of each Class 

 with regard to their adaptation to their mode of life as, for 



