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The Determination of Hesperidae. 

 By Eugene M. Aarox. 



It is with much pleasure that I have read the first instalment of 

 ^Tr. J. B. Smith's novel and very instructive address to the Entom. Club 

 of the A. A. A. S. The younger students, as well as some of us who 

 have been in the field for some years, owe ]\Ir. Smith a vote of thanks 

 for the address, shcnving, as it does so clearly, where we can find willing 

 specialists with capable collections to whom we can refer our unde- 

 termined specimens. 



On page 109 Mr. Smith speaks as follows of my own collection : 



" In the fa.mi\y //espen'da of the Rhopalocera, the collection of 

 Mr. Eugene M. Aaron of Philadelphia is excellent. ^Ir. Aaron has 

 spent much time and money to complete his collection in this family ; 

 but owing to his numerous business engagements cannot unfortunately 

 devote much time to his collection at present, (7nd cannot do much for 

 seekers of information in this family." 



The italics are mine ; and it is of the accuracy of the statement 

 contained in this last clause of which I wish to write. When it was 

 penned by Mr. Smith it was an exact statement of the facts of the case 

 as they have existed for the past three \-ears. Eortunatel}' for my peace 

 of mind, for my collections have been at all times in my thoughts, I 

 have been able to make business arrangements during the past summer 

 which will give me for the six months to come, a considerable 

 amount of time to give to the study of the Hesperid^F and to the exam- 

 ination and determination of material from collectors of this puzzling 

 family. 



I have explained elsewhere (Papilio, Vol. IV, p. 171) the methods 

 adopted by me in 1880 for the determination of all Hesperida;, and in 

 fact all Rhopalocera from America north of the Isthmus of Panama. 

 These methods are still pursued by me, and at this writing, my Ed- 

 wards' and Kirby's Catalogues are complete so far as it is possible to 

 make them from the Zoological Records and from the unequaled libraries 

 of the American Entomological Society and The Academy of Natural 

 Sciences of Philadelphia. In print or in IMS. copy I have the original 

 description of every species of the Rhoi)alocera in America north of 

 Mexico, and in the HesperidLC north of the Isthmus. For ready refer- 

 ence I have had the leading writings of Hiibner, Geyer, Felder, La 

 Sagra, Boisduval, Herrick-Schaffer, Poey, Speyer, ]\Iabille, Oberthiir, 

 Staudinger, et al., carefully translated into English and these MSS. 

 brought together in a bound form and copiously indexed. All corre- 



