XXII PREFACE. 



family is far more remunerative, both in pleasure and in use- 

 fulness, than the random description of numerous new species." 



But little reflection is necessary to prove that monographic 

 work is the most advantageous form of work in descriptive 

 entomology. It implies the greatest concentration of one's 

 working power , and for this very reason, its greatest economy ; 

 its products are the most lasting, because a good monograph 

 is not easily supplanted ; they are the mi st useful, because they 

 facilitate and encourage the study, instead of obstructing it, as 

 some other kind of work is liable to do. 



The productions of unconsciencious and incapable writers 

 ought not to obstruct better workers and thus to impede the 

 progress of science. Let no one, attempting a monograph, be 

 deterred by the number of earlier descriptions in the same family. 

 The principal effort should be, to collect an abundant material, 

 representing as nearly as possible the fauna of a given region 

 in the family selected for work. With such a material the 

 identification of previous descriptions becomes comparatively easy. 

 "With some perseverance and attention, the available descriptions 

 will soon be identified and the residue may be neglected, as 

 useless. It may happen that the whole, or nearly the whole 

 of the previous descriptions proves to be unavailable; let not 

 the w< rk be prevented by it. Of the thirty -two earlier de- 

 scriptions of North- American Dolichopus, all but two, were un- 

 recognizable; this did not prevent Dr. Loew from writing a 

 standard monograph of the genus. The next step for the 

 monographer should be, to prepare descriptions of all the species, 

 because it is a bad plan, in a monograph, simply to refer to the 

 descriptions of previous authors *). By means of analytical tables, 

 or of figures, the descriptions should be rendered accessible, 

 enabling every one, with the monograph in hand, to get at the 

 name of a given species. 



*) Erichson expressed the same views in the Preface to his Ento- 

 mographieen, and the passage deserves to be reproduced here: 



r Beseb.reibungen nener Arten scheinen mir in den meisten Fallen nur dann ein n 

 wesentlichen Fortschritt der Wissenschaft zu bedingen , wenn eine Uebersicht fiber die Ab- 

 tlieilung, der sie angehoren , damit verbunden, und diesn als ein Gauzes betrachtet wird. 

 Es kann in solchen Arbeiten oft hinreichend sein, bci bekannten Arten auf schon vorhan- 



