LETTER OF MAY 15TH, 1859. 21 



to describe it under the name of Diacopia. If you can en- 

 lighten me on the subject, your valuable aid will be highly 

 appreciated. 



As soon as I can arrange my materials, I intend to begin 

 to describe Tineina in the Proceedings of the Acad. of Nat. 

 Sciences, and will send them to you regularly. And what 

 will be still more acceptable, as soon as I have supplied a few 

 friends and the Cabinet of the Academy with specimens I 

 have classified, I will be happy to supply your cabinet also, 

 but I will promise to send you those alone which I have 

 classified or cannot classify. I can do this without the least 

 expense to either you or myself; the Smithsonian Institution 

 will take charge of these transmissions, and deliver them to 

 you without any expense. Their exchanges with Europe 

 take place but twice a year however, and as the packages are 

 all included in one large box, it might not be the safest mode 



that could be adopted. 



* * * ***** 



I never received the number of the " Intelligencer" in 

 which you noticed the differences between L. Acaciella and 

 the American Robiniella. I met, however, during last 

 spring Baron Osten Sacken in Washington city, and he 

 informed me he had visited you when in London and that 

 you had given him the article. He was kind enough to 

 send it me the next day, but his messenger lost it on the 

 way. 



Is Professor Frey's work the only good one on Tineina 

 you can recommend to me? Are there none in French? 

 I do not yet read the German with sufficient ease to enable 

 me to use the former to advantage. The recognition of 

 genera is much more laborious to the American student than 

 to the Continental one, for we have no cabinets of classified 

 specimens that we can consult. Your very excellent " In- 

 secta Brit." and the " Nat. Hist, of the Tineina" have been 

 of great value to me, but I suppose there are many genera 

 which are not included in the former, and it will perhaps be 

 years before the subject is exhausted in the latter. If you 



