and scientific institutions. We have, however, been advised from sev- 

 eral sources to extend the edition, so that the various collectors 

 throughout the country might have the opportunity of becoming ac- 

 quainted with at least an illustration of some of the rarer species. To 

 do this it has been necessary to choose .some form of reproduction 

 from the photograph, and after a careful examination of the various 

 proofs submitted we have chosen the half-tone in preference to the 

 heliotype, as the maculation, in spite of the fact that a certain portion 

 of the finest details are inevitably lost by the use of a screen, appeared 

 to be more clearly defined in the former process. The greatest draw- 

 back to this method is found in the case of those moths with dark 

 primaries and white secondaries; the former prevent the use of an 

 entirely black background and the latter have shown up so poorly on 

 the white background that it has apparently been necessary for them 

 to be retouched in the half-tone, a process which has only succeeded 

 very indifferently in several of the illustrations, and, while not per- 

 haps seriously afifecting the figure as a means of identifying a species, 

 has certainly not added to the artistic appearance of the plate. By 

 the use of a gray background we hope to obviate this defect in our 

 further publications and meanwhile crave the indulgence of the reader 

 who finds trouble in recognizing certain of the fig^ires. 'Experiantia 

 docet,' and probably no one is more alive than ourselves to the defects 

 of the work or more anxious to eliminate these objectionable features 

 in future publications. 



In the letter-press, besides the name, locality, and sex of the speci- 

 men, we have in many instances made further notes on the species 

 and its synonymy; in certain species, notably the Eiixoa group, ab- 

 solute identification has been impossible in view of the great variation 

 known to exist in this genus and our imperfect knowledge of many of 

 the type specimens. 



