Brazilian Entomology. 213 



corresponding to the different sizes of the tufts in the 

 several species. The male of Ituna sometimes protrudes 

 his tufts, when he is seized, so that in this butterfly the 

 odour may serve both to repel enemies and to allure fe- 

 males. The well-known " sexual spots," or rather pouches, 

 on the first median nervure of the hind wings of D. Erip- 

 pus and Gilippns, which ai'c much larger in this latter 

 species, appear to be, by their microscopical structure, 

 scent-producing organs ; but as they open only by a nar- 

 row slit, odours could hardly be freely emitted. There is 

 one curious circumstance, which may perhaps throw some 

 light on their as yet very doubtful function ; the scales, 

 though perfectly preserved everywhere else, are often 

 wanting at the entrance of the pouch, as if they had been 

 scoured aAvay by something introduced into the slit. It 

 would be Avorth while to see whether this be the case with 

 other species of Danu'is also. Might not the tufts be 

 introduced into the pouches to be impregnated there with 

 odoriferous matter ? 



B. Ithomia group. 



The males have a tuft or pencil of long hairs near the 

 anterior margin of the hind wings,* which in all our 

 species emits a more or less distinct odour. The odour 

 is rather strong- and most agreeable, resembling vanilla, 

 in Dircenna Xantho, rather faint in Ceratinia Eupompe 

 and Ithomia Sylvo ; it is still more so in Meclianitis 

 Lysimnia, where I perceived it distinctly in but few 

 males. In Thyridia Megisto the odoriferous tuft is not 

 limited to the male sex ; it exists in the females also, but the 

 hairs are shorter and less numerous and the odour emitted 

 is much fainter than in the males. The males have a well- 

 defined brown spot, covered by the tuft ; this is hardly 

 distinguishable in the females. As the tuft exists in all 

 the males of the group — which contains about a dozen of 

 genera wdth more than two hundred species — as it is 

 Avanting in almost all the females, and as in Thyridia 

 Megisto it is much less developed in the female sex, there 

 can, I think, hardly be any doubt that it has been ac- 

 quired as a sexual attraction by the males of the common 



* There are two widely-separated tufts in the male of a small species 

 of this group, resembling in size and colour Cyllopoda dichroa, one of 

 our Olavcopidce. 



