lviil PREFACE. 



concise definition, they answer the ends proposed ; namely, clearness 

 of arrangement, brevity of description, and facility in finding species. 

 But the human mind is ever prone to extremes, and the passion for 

 dividing and subdividing, and giving names, may become as great an 

 evil as that which led the followers of Linnaeus to deprecate all divi- 

 sion, and to view with abhorrence the slightest attempt to break up 

 the old groups. Now the point at which these artificial genera and 

 sub-genera should stop is, where they can be no longer defined with 

 reference to the end proposed ; that is, when their peculiarities are 

 so slight that they cannot be pointed out in a clear and comprehensive 

 manner. When, to make them intelligible, it becomes necessary to 

 draw up long and perplexing characters, the very object of their 

 makers is defeated. No clearness is gained, no facilities of research 

 afforded ; the student is bewildered, and the experienced naturalist 

 consumes more time in reading over and comparing these generic 

 chapters, than would enable him to glance his eye over twenty good 

 specific characters. The tedious and intolerable length of such defini- 

 tions, it must be confessed, is inevitable ; for their authors, not being 

 acquainted with the principle of variation in their group, are obliged 

 to specify all its characters ; whereas, if the group was a natural one, 

 and its true distinctions had been studied, its essential characters, as 

 we shall repeatedly exemplify, might be expressed in two or three 

 lines. Fortunately, the only group in Ornithology which has appa- 

 rently suffered from this evil is that of the Falconidcs. In Entomo- 

 logy, however, its pernicious consequences are nowhere so conspicuous 

 as in the recent works upon British Insects : where the generic 

 characters, for the most part, are so complicated and prolix as to 

 occupy half a page. 



To show that this passion for genus making among us has reached 

 a point bordering upon the ridiculous, I need only state a fact, asserted 

 by one who seems not to be conscious of following in the same track, 

 " that the Musca putris of Linne has actually been converted into 

 three species, belonging to two genera*." 



* Stevens, Catalogue of British Insects, Pref., p. xiii. 



