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 

 among naturalists under the denomination of natural charac~ 

 ter. When this description is full, and constructed with 

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

 a 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 Linnasan 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, &c. 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, which consist of genera, 

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

 trod action of new terms is easily avoided, by denominating 



