CHAPTER XIV 

 CLASSIFICATION AND NOMENCLATURE 



Whenever one has to deal with a great many objects of varied char- 

 acter it becomes necessary to arrange them in such a manner that any 

 additional object can at once be put in its proper place with respect to the 

 others, that any particular object can at once be found, and that they may 

 be referred to by groups. Such arrangement and grouping are called 

 classification. It is imperative in the arrangement of a library and 

 increasingly so as the library grows in size, is necessary in every mercantile 

 establishment, and to a degree even desirable in the handling of objects in 

 our homes. 



90. Definition. — Zoological classification may be defined as the group- 

 ing and arrangement of animals in such a way as to facilitate reference 

 to them. If this grouping is based only upon the place where animals Uve 

 or upon their form and structure, without regard to any relationships 

 which may exist, it is termed artificial classification. If, however, an 

 arrangement is secured such as to bring out the degree of relationship, 

 assuming all animals to be related and to have evolved from the living 

 matter first developed upon this earth, it could be called a natural 

 classification. The basis of zoological classification is essentially artificial, 

 but in so far as knowledge permits, zoologists endeavor to make it 

 natural. 



91. Arrangement of Groups of Animals. — The groups into which 

 animals are arranged present a graded series, beginning with the whole, 

 leading through those of gradually diminishing extent, and ending with 

 each particular kind, which is a collection of like individuals. Generally 

 speaking, any particular group will contain several groups of the next 

 lower rank. It is evident that the characteristics of any one group will 

 involve details of structure less fundamental than those of the next higher 

 group and that, on the other hand, the characteristics of any group will be 

 only those in which all the lower groups contained in it will agree. The 

 names of the most widely used of these groups, in order of rank, illustrated 

 by reference to a particular species of animal, are as shown on page 59. 



These group names in their plural form may be treated either as Latin 

 or as English words, as, for example, phyla or phylums, and subphyla or 

 subphylums; or they may be given only their Latin plural, as genera; 

 or only their English plural, as in the case of all the other groups above. 

 The word species is the same in both singular and plural forms. 



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