RILEY — HACKBERRY BUTTERFLIES. 201 



B I BLIOGRAPHICAL. 



For forty years past these two butterflies have been known in 

 entomological works by the names of Apatura celtis Boisd. and A. 

 Clyton Boisd. Even in Mr. Edwards's recent work* these familiar 

 names were retained. But in Mr. Scudder's Revisionf these 

 insects are referred to under the generic name Doxocopa and the 

 specific names which I have here employed. 



Of the generic name it need only be said that Apatura was cre- 

 ated by Fabricius in 1807 ; Doxocopa by Hiibner in 1816. From 

 information kindly communicated by Mr. Scudder, the latter ge- 

 nus seems to differ from the former principally in the antennae 

 being proportionally more slender, the club shorter and less 

 uniform, the palpi more slender and yet shorter, and the legs 

 also more slender ; while the hind wings in the male Apatura are 

 not hollowed out as in Doxocopa, This last character is of little 

 value, as it is variable in the same species^ The other points of 

 difference also appear trivial indeed when we consider the many 

 points of resemblance. It is reasonable to suppose that many of 

 the honored writers on diurnal Lepidoptera, since Hiibner's time, 

 have been familiar with his diagnosis of Doxocopa^ and that they 

 ignored the genus because they considered that the characters 

 were not sufficient to separate it from Apatura. Kirby, as late 

 as 1871, did so. Opinions will differ as to what should consti- 

 tute a genus, and my own opinion is expressed in the name I here 

 employ. Mr. Scudder may be able by study of the preparatory 

 stages to establish more emphatic differences in his forthcoming 

 work. If so, Doxocopa will doubtless be employed for our spe- 

 cies, but it will be Doxocopa Scudder and not Doxocopa Hubner, 

 as the latter knew nothing about those differences. Until that time 

 I have thought best to follow preceding authors. Judging from 

 figures of the European Apaturas^ the most important differences 

 between them and our two N. A. species will be found in the 

 chrysalis state, and principally in the shape of the cremaster. 

 The horns of the European larvae are less branching, and the 

 notum of the thorax in the chrysalis is more depressed ; but our 

 two N. A. species also differ in these characters. 



* The Butterflies of N. A., by Wm. H. Edwards; Philad., 186S-72. 



t Sys. Rev. of Some of the Am. Butterflies, by S. H. Scudder; Salem, Mass., 1S72. 



