120 THE entomologist's record. 



method of producing transparency is by a simple process of modifying 

 the scales into hairs. In the Ithomiinae, where transparency is sO' 

 general, one forms the opinion that this is brought about by a com- 

 mon cause. That cause is probably for effacive coloration, as these 

 insects are wonderfully inconspicuous at a very short distance. With 

 the prime rauun iVetre being the same, one would expect the method of 

 obtaining it to be the same, and an examination of many different 

 species in different genera shows this to be so. In the genera Lcuco- 

 thyris, Ithomia, Scada, Kpiscada, Pteronyniia, Heteroscada, Hyposcada, 

 Hynienitis, Heterosais, Calluleria and (Jeratinia, all the species ex- 

 amined show that there are two different-shaped scales, placed alter- 

 nately, (1) a long unindented scale, and (2) a broad toothed scale. 

 Where a species has developed perfect transparency, such as Hymenitis 

 dircenna or Itlioiiiia pelliicida, the long narrow scale has developed into 

 a single hair, and the broad scale has developed into a Y- or V-shaped 

 structure. Other less developed transparent species show that the Y 

 or V is in reality the shell only of the broad scale, as the membrane, 

 so to speak, has receded until only the frame is left. Certain 

 species, such as Scada theaphia, have the scales completely modified 

 in this manner, but have not lost any of their number, and only 

 semi-transparency is afforded in this way. In Ceratinia, such as 

 in the (^ s of C. tricolor and C. euclea, the long narrow scales are com- 

 pletely developed, while the broad scales have only commenced 

 development by shrinkage of the membrane of the scale. In Hynienith 

 dircenna, It/ioiiria pelbicida, and, probably, in all the genera where the 

 scales are sufficiently modified, it is remarkable that only the single 

 hairs, or modified narrow scales, come off", while the double or bifur- 

 cated hairs remain in position. Although outside the strict sphere of 

 this paper, I should like to say that this alternate long and narrow, 

 and short and broad scalmg, is probably a thoroughly sound character 

 on which to diagnose an Ithomiine, as even in Metluma confiisa and^ 

 Thyridia paidii, very different-looking insects, the scaling is the same. 



In marked contrast with the Ithomiines are the transparent Eryci- 

 nids. We have already examined J^jsthe in opsin sericina, and found that 

 there are two layers of scales, each of which is transparent. We have 

 examined the Stalachti.s species, S.phaediisa and iS. erelina, and found 

 that there are two layers of scales, the upper of which' develops into hairs,, 

 and the lower into transparent scales. In the genera Zeoma, Z. »ylpha 

 and Z. chorineus show that there is only one shape and one layer of scales, 

 that these become greatly reduced in size, and very greatly reduced in 

 numbers. With these facts in view we may ask ourselves if our- 

 classification of these genera into one family is on a sound basis. 



It has, I fear, been quite impossilDle to do more than touch on a 

 subject that is as vast as it is fascinating. I, however, hope that I 

 may have stimulated other entomologists to work at this subject, as I 

 know there are many willing shoulders anxious to push forward the 

 wheel of research. 



APPENDIX. 



Napeogenes potaronus, n.sp.- — Forewing black and transparent. 

 A large heavy black band from costa across the end of cell nearly to 

 the marginal black band. Costa black, except just beyond the median 

 band, where it is white. Apex broadly black with traces of some 

 whitish marks. Inner and outer margins black, the remainder of the 



