PREFACE. 



The object of the present work is to furnish in a compact form, good 

 colored illustrations of all the species of ZygcenidcE and Bombycidce found 

 in North America, north of the Mexican boundary; with accompanying 

 letter press, in which it is intended to embody everything of interest in 

 relation to each species, which may have appeared in print, with such 

 additional information as I may be able to secure from original sources. 

 There is nothing at present which covers this ground. Many species 

 are unfigured, others have been figured only in black and white ; the 

 illustrations being at the same time scattered through many works. In 

 relation to the letter press, the latter remark is equally true. The 

 synopsis of the Lepedoptera of North America, by Morris, with appen- 

 dix, by Clemens, while a valuable vvork, is uiulIi bohinJ our present 

 knowledge of the groups ; and it is moreover unaccompanied by 

 plates, without which the determination of the species of some genera, 

 such as Arciia, is nearly impossible. It is hoped the present effort 

 will supply a want which I have myself seriously felt in studying these 

 groups, and which I doubt not, must have been equally patent to the 

 rapidly increasing number of entomologists in the United States. 



Many species exist in cabinets only as unique specimens ; and a 

 large number are so rare that few possess them. The difficulty of 

 procuring these for the purpose of figuring them, will preclude the 

 possibility of commencing at the head of the list and figuring the 

 species seriatim, in natural sequence, so that the insect will be figured 

 as I can procure them, precedence being given to those that are new^ 

 or but little known, an effort being made however to present all the 

 species of a genus in the same number, where it is possible to do so. 

 In the letter press it will be my endeavor to make the synonymy 

 and history of each species as complete as possible, using the original 

 descriptions where they are sufficiently accurate, and adding thereto 

 the characters of the larv^ and their transformations where known. 



The work will probably extend to about thirty parts, which it is 

 intended to issue at intervals of about six weeks, in octavo size, uniform 



