100 LEPIDOPTERA. 



had long been used for the discrimination of species. That 

 the species must in the first place be divided into two main 

 groups, in one of which the antennae of the male are pecti- 

 nated to the tip, whilst in the other the last 8—10 joints form 

 a club, had long been evident to me. The relative lengths 

 of the antennae, in proportion to the discoidal cell of the 

 anterior wrings, had been used by the best authors for the 

 distinction of species ; jet I had already observed, that in 

 specimens which certainly must belong to the same species, 

 the antennae appeared to differ in length. I therefore had 

 recourse to counting the individual joints of the antennae 

 under the microscope, since one can only undertake to count 

 them accurately under a considerable magnifying power. 

 In order to be quite sure I counted the joints of one and the 

 same antenna several times ; I counted the joints of both 

 antennae of the same specimen, and I counted besides the 

 joints in all the specimens which I possessed of some species, 

 and at last I arrived at the melancholy result that the num- 

 ber of joints may vary considerably in one and the same 

 species. Differences of from four to six joints were not un- 

 usual, and even sometimes of eight. Nevertheless, I arrived 

 at the result that certain species had, on the average, always 

 a greater number of joints than others. 



The pectinations first begin at the fourth joint, though 

 sometimes the third shows a very small projection, other- 

 wise one can only distinguish the three first joints after 

 removing the scales — with the scales on they appear to form 

 together one long basal joint. Then follow the joints with 

 pectinations, and these certainly arise at the bases of the 

 joints, not at their ends (as in Bembecia Hylmformis). 

 Towards the apex the pectinations in the species of the first 

 group diminish more or less rapidly in length, on the sub- 

 terminal joints they often only appear as dentations; the 



