384? CHARACTERISTIC. . 250. 



being in general so great, that they cannot easily be miss- 

 ed, even by the application of this instrument. If the 

 differences be small, and their distinction require on that 

 account a higher degree of accuracy, it will be necessary to 

 recur to the reflective goniometer. 



It will seldom be necessary to read over the whole of any 

 character of a class, order, genus, or species, excepting 

 those which comprise the individual ; one term that does 

 not agree sufficing for its exclusion. Thus even the cha- 

 racters of the orders, though the longest, will not be found 

 troublesome. 



The application of the Characteristic has been facilitated 

 in a great measure by separating the absolute characteristic 

 marks from the conditioned ones. It becomes still more 

 easy and expedititious, by taking particular notice of some 

 characters, which might be termed prominent. Such are a 

 metallic appearance ; a high degree of specific gravity, 

 particularly if the appearance be not metallic ; and a high 

 degree of hardness. The observation of these will imme- 

 diately decide whether an individual can belong to any 

 particular class, order, genus, or species. It is understood, 

 that if it be not thereby excluded, the other characters 

 must next be examined, till either an excluding one be 

 found, or if not, the individual may be considered as be- 

 longing to that class, order, &c. with which it has been 

 compared and found to agree. 



. 250. DETERMINATION OF INDIVIDUALS, BY MEANS 

 OF THE CHARACTERISTIC. EXAMPLE. 



An individual, which has been carried through 

 the characters of the classes, orders, genera and spe- 

 cies, and whose systematic denomination has thus 

 been found, is said to have been determined. The 

 determination is complete, if the individual has been 

 traced to a species ; it is incomplete, if it has only 

 been brought under a certain order or genus. 



