CLASSIFICATION. 53 



randum of one of its most characteristic marks. In 

 naming any species of a genus, the name of the latter 

 is employed, accompanied by a second denomination, 

 which usually indicates some character by which the 

 species mentioned is distinguished from the other 

 members of the genus, thus each species bears a 

 double name, one belonging to itself in particular, 

 the other common to it and its congeners. This 

 system of nomenclature is the same in principle with 

 our own constant practice in common parlance, when 

 we employ a well-known substantive in a generic 

 sense, and qualify it to suit particular cases by the 

 addition of an adjective. The names of the families 

 and sometimes those of the tribes are formed from 

 the name of the genus which exhibits their characters 

 in the greatest perfection, and which is thence called 

 their type, by the addition of a peculiar termination ; 

 the names of the higher groups, like those of the 

 genera, are usually indicative of the leading common 

 character of their members. 



From the above description of the mode in 

 which a system is to be produced, it would appear to 

 be a very simple matter, but in practice we find that 

 nothing is more environed with difficulties. This 

 will be easily understood if we consider that, besides 

 furnishing us with a means of ascertaining all that is 

 already known with regard to any natural object 

 which may fall in our way, a good classification is 

 expected also to show us the mutual relationships 

 of the different objects ; and as the same phenomenon 

 is usually capable of being interpreted in several ways, 

 according to the peculiar views of the observer, it is 

 evident that, however desirable uniformity of system 

 may be, it is a thing for which we can scarcely hope. 



