16 



DR. BRACKENRIDGE CLEMENS LETTERS. 



If you read German I would recommend to you Frey's "Tineen 

 und Pterophoren der Schweiz ;" though it has no plates, it is a 

 most valuable work, and I think it more interesting than my 

 volume of the " Insecta Britannica." 



III. 



Easton, Pennsylvania, United States, 

 December 29th, 1857. 



[Received 18th January, 1858.] 

 I write merely to correct a mortifying error in my 

 delineation of the neuration of the anterior wing of Litho- 

 colletis Robiniella. When I wrote I was quite confident of 

 its correctness from having made frequent and, as I supposed, 

 careful examinations with single lenses, magnifying from 

 twenty to about eighty diameters. But being unable to 

 comprehend the meaning of the disagreement between your 

 delineation in the same genus and mine, I was induced a 

 short time since to examine critically a copy of that which I 

 sent you, when I became convinced that the wing must be 

 represented upside down. A careful denudation of another 

 wing rendered this painfully apparent, while, at the same 

 time, the renewed examination, much to my surprise, re- 

 vealed I had likewise omitted the branch of the subcostal 

 nervure, which closes the discoidal cell. The representation 

 I now enclose I am sure 

 is correct, and an exami- 

 ation of it will show you 

 there is no essential diffe- 

 rence in the neuration of 

 Lithocolletis Robiniella 

 andiL.3Iessaniella,i[ioug\i 

 found in opposite hemispheres. 



I shall be much obliged to you if you will also make a 

 correction in the text of my former letter, and substitute 

 "predominant" in place of " dominator" characters; and, 



