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APPENDIX 
Besides these species, I have examined the costal folds of several 
others whose names I do not know. Inasmuch as observations such as 
these, which cannot be verified by others because the species are unknown, 
are of little value, I will confine myself to a few words on the most notable 
forms of scales or hairs which I found in these undetermined forms. 
In a species of Telegonus (with transparent yellow spots, and a large 
silvery spot on the under surface of the hind-wings) the costal fold 
contained chiefly hair-like scales, transparent and very long (about 
0*36 mm.) terminating suddenly in a very slender thread (PI. G, Fig. 31 a). 
There were also present other scales (Fig. 31 5) like the smaller ones of 
Thymele proteus (Fig. 29 Z>), and a few fragments of jointed hairs. 
In another species, the joints, which are very variable in length and 
breadth (PI. G, Fig. 32), were united by very long filaments, which still 
adhered to the separated joints. 
Finally, in a species closely resembling Achlyodes thraso , Hiibn., the 
costal fold, which is very narrow, enclosed lanceolate, more or less opaque 
scales (PI. G, Fig. 33 c), transparent threads (Fig. 33 a), remarkable for 
being furnished with a sort of transparent, fusiform root, or vesicular 
appendage, of about 0*025 mm. long by 0*008 mm. broad. Among other 
Hesperidae I once met with a similar root on a single scale in the fold of 
Telegonus mercatus (PL F, Fig. 11 a). In the sub-family of the Pierinae 
the scales dispersed over the surface of the wings in the male are almost 
always furnished with vesicular appendages. 
As to the function of the folds in the Hesperidae , I think there can be 
no doubt that they belong to the class of scent-organs, which, infinitely 
diversified, distinguish the males of so many other Lepidoptera. A 
structure very similar to that of the Hesperidae is found in certain 
species of the genus Papilio , not, indeed, on the costal margin of the fore¬ 
wings, but on the inner margin of the hind-wings, which is folded over, 
and covers either a pencil of long hairs, or a dense pale down. In Papilio 
protesilaus the black brush exhales a strong, disagreeable odour, whereas 
the pale down of P. nephalion diffuses a pleasing aroma. That the 
function of the marginal fold on the hind-wings of Papilio is that of 
[preparing and diffusing] odours is evident, and by analogy it is also the 
use of the costal fold of the Hesperidae ; for it is in every way probable 
that these similar structures exercise the same function. 
