318 PRACTICAL AND SCIENTIFIC ZOOLOGY. 



looked upon as oracular. It may, nevertheless, hap- 

 pen, even in systems grounded upon universal prin- 

 ciples, that what appeared in the first instance an 

 example of defective, unnecessary, or unnatural com- 

 bination or arrangement, may be truly unexceptionable 

 when viewed with reference to those general principles 

 upon which the system itself is founded. 



(SS^.) Hence it becomes necessary that a general 

 knowledge of the principles of natural arrangement 

 should be first acquired ; for, as these principles are as 

 conspicuous in the smallest groups of nature as they are 

 in the largest, they form the basis of every true com- 

 bination above that of a collection of individuals of the 

 same species. If the student resolved, for instance, to 

 confine his attention to the parrot family, of which there 

 are probably 200 species, he will discover that the 

 natural arrangement of these species, among themselves, 

 is regulated precisely by the same laws as those which 

 divide the classes of vertebrated animals. In like 

 manner, if he studies the lepidopterous order of insects, 

 he will find their natural series to tally not only with 

 those of the parrots and the vertebrated classes, but 

 also (and, of course, more intimately) with those of the 

 apterous and the winged insects. A general idea, there- 

 fore, of those fundamental principles of classification by 

 which all these dissimilar groups are naturally arranged, 

 is indispensable. AVhen this is acquired, the student is 

 qualified to enter upon the details of that particular 

 portion he has selected for study ; he will receive an 

 elevated pleasure in tracing these principles in the 

 arrangement of the objects before him ; and he becomes, 

 in some degree, qualified to judge of their correctness. 

 Having, in the last chapter, intimated those requisites 

 which should prepare him for this enquiry, we now 

 proceed to a familiar explanation of these principles. 

 The student, thus prepared, will be qualified not only 

 to understand the former disquisitions in this volume, 

 but will peruse those which succeed with feelings of 

 interest he could not otherwise entertain. 



