mi KFACE. 



The basis of good work in any science is a knowlcfIf;re of what ha.-? 

 been done in tlic past. This proposition docs not need argument for 

 its support, and it follows, logically, that any work which facilitates 

 tlie acquirement of this basic knowledge and brings together system- 

 atically andcriticallytheresults theretofore oi)tained will also facilitate 

 the advance of the science. The study of the North American Noc- 

 tuidai has been seriously embarrassed by the difficulty in acquiring 

 this foundation; not always because books were lacking, but often be- 

 cause the knowledge was contained in so many without an index to 

 guide the student. Since Mr. G rote's catalogue of 1874 no comprehen- 

 sive bibliographical work on this family has been published, while the 

 number of species has nearly doubled and the literature has increased 

 enormously. This state of affairs results in the formation of card cata- 

 logues or indices made by each student to facilitate his own work, and 

 gradually he becomes familiar with the knowledge published by his prede- 

 cessors. But this does not help others, and the same work is done over 

 and over again by those engaged in the same fields of study. It has also 

 been extremely difticult, even after becoming familiar with the literature, 

 to ascertain exactly what species were really before the older writers. 

 Characters now regarded as essential were not even noted by them and 

 descriptions which, with the few species at hand, were characteristic 

 and pointed became vague and indefinite when larger material brought 

 us many and closely allied species. The greatest bugbear to American 

 Le]udopterists has been the work of Francis Walker in th(; catalogues 

 of the British Museum. Mr. Grote after twenty years of study in the 

 Noctuida; had failed to identify a large percentage of the species, while 

 even of the species described by Guenec forty years ago, a number are 

 still unidentified in American collections. For ten years 1 have been 

 accumulating material for .'i nmnograph of the i!^orth American Xoc- 

 tuidie, and have examijied about all the books obtainable in Philadel- 

 phia, New York, Washington, and elsewhere, and have jiurchased 

 papers on the subject when<'ver opportunity offered. 1 have had, dur- 

 ing that time, unusual opportunities for studying the material in the 

 leading American collections, and some of the results obtained have 

 been published in my various "Contributions toward a monograph of 

 the Noctuidui of Temperat(! North America." 



