158 PHILOSOPHY OF ZOOLOGY. 



3. Generic Description.'-^As the generic character is in- 

 tended solely to facilitate investigation, its requisite brevity 

 precludes the possibility of enumerating all the properties 

 which the species possess in common. This defect, how- 

 ever, is supplied by the description, which is better known 

 anions: naturalists under the denomination o^ natural charac- 

 ter. When this description is full, and constructed with 

 due regard to the characters of the higher groups, it saves 

 ^ great deal of repetition in giving the description of the 

 species ; and, during its composition, unfolds the peculiar 

 marks by which they are to be distinguished. It power- 

 fully exercises the judgment, and seldom fails to unfold 

 new views of the natural affinities of animals, and the mo- 

 difications of their several organs. 



In the Linnaean System, the divisions of a higher kind 

 than genera were limited to two in number, viz. orders and 

 classes. Classes constituted the primary divisions, and in- 

 cluded orders : these last included the genera and species. 

 The modern improvements of science, and the vast addi- 

 tions of new species, have multipled the number of divi- 

 sions in the system to an extent greatly beyond the five origi- 

 nally employed by the Swedish naturalist. In many cases, 

 they exceed twenty in number. In order to give to each of 

 these groups an appropriate title, naturalists have denomi- 

 nated them divisions, classes, orders, tribes, legions, families, 

 sections, subdivisions, Sec. We have already stated the want 

 of co-ordination between these groups, and are therefore 

 disposed to prefer distinct appellations for each, expressive, 

 if practicable, of their essential character, rather than to de- 

 signate them by terms, which, while they occur frequently, 

 have never the same equivalent expression. 



In the construction of Families y which consist of genera, 

 related to each other by certain common properties, the in- 

 troduction of new terms is easily avoided, by denominating 



