16 THE GREAT DIVISIONS OF THE ANIMAL KINGDOM. 



animals that we are enabled to classify them, and to distinguish 

 them with certainty ; but in order that a classification may be as 

 useful as possible, it must serve to point out the resemblances, 

 greater or less, which are remarked amongst them. Also, in the 

 classifications called the natural methods or orders, the only really 

 good ones, the characters upon which the divisions and sub-di- 

 visions of the animal kingdom are based, are selected in such a 

 manner that each group includes only such species as resemble 

 each other the more in proportion as this group itself is of a less 

 elevated rank in the classification. The animals of the same 

 genus, for example, will differ much less from each other than 

 those of two genera of the same family, and these latter will re- 

 semble each other much more than those belonging to different 

 orders, and in a still stronger degree, than those of different 

 classes. 



The natural classification is, in a manner, a synoptical view of 

 all the variations met with in the organization of animals, and in 

 knowing the place which any animal occupies in such a method or 

 classification, we know by it alone the most remarkable features 

 of its organization, and the manner in which its most important 

 functions are performed, that is to say, the most important part 

 of its history, because its habits are always correspondent with 

 its conformation. 



DIVISION OF THE ANIMAL KINGDOM INTO BRANCHES. 



16. In ranging animals according to their different degrees of 

 resemblance and according to the differences more or less con- 

 siderable which distinguish them, we first remark, that there 

 exists in the animal kingdom, four principal types according to 

 which nature seems to have constructed all these beings ; they 

 are divided into four great divisions or BRANCHES, namely : 



1st. Animalia vertebrata vertebrated animals. 



2nd. Animalia mollusca molluscous animals. 



3rd. Animalia articulata articulated animals. 



4th. Animalia radiata radiated or rayed animals or zoophytes. 



17. The following table presents the principal characters which 

 distinguish these great divisions of the animal kingdom : 



are the characters of animals selected in the classifications according to tho 

 natural methods ? What does natural classification enable us to know ? 

 Do the habits of an animal correspond to its organization and conformation ? 



16. In classifying animals what do we first observe? What arethegrcat 

 divisions of the animal kingdom? 



17 (O" The folio icing questions ore answered in the table.) What are the 

 leading characters of animals belonging to the branch of vertebrated animals? 

 How is this branch divided ? What sort of blood have these animals ? 



