a large Heliconine collection made in French Guiana. 351 



1915 collection; for although the collection is eight times 

 the size the percentage of streaked and black hind-winged 

 forms is quite remarkably close. 



The total number of H. erato, the companion species of 

 the second great division of Heliconius, is 1,123. Only 

 46 of this large number show a black hind-wing. In 1915 

 the number of black hind- wing forms was 6 out of 155. 



It is difficult, if not nearly impossible, to get a really 

 iust set of figures for comparing the darkened fore-wing 

 forms of both melpomene and erato. Melpomene in its 

 cybele section and its thelxiope section shows completely 

 darkened fore-wing in the forms funebris and stygianus 

 respectively, but in the all-black hind-wing no wholly 

 blackened 'fore-wing form has yet occurred, this forming 

 a wholly black insect. In erato the form oberthuen is 

 the darkest known form from this region, but this shows 

 some slight remnant of the yellow, and there are all 

 gradations up to vesta. It is thus difficult to know how 

 many erato to include, and we fancy we really included too 

 many in our table given at the top of p. 429 of our former 

 paper. Keeping strictly to the very darkest fore-wing 

 forms of both species, we get these comparisons :— 



This as a comparison between the two species is prob- 

 ably approximately correct, but it is hardly right to 

 compare the 1915 figures, as we realise we included too 

 many forms which "were not sufficiently extreme. The 



