656 
APPENDIX 
margin, and also covered, in G. cijoris , with a mane of long hairs. In the 
males of almost all the Brassolinae —large, Morpho- like, but less brilliantly 
coloured insects, which are on the wing especially in the early morning 
and towards the evening—the hind-wings are furnished with scent-organs 
in very different positions and of various forms. I noticed an unusually 
strong musky smell in a Dasyopthalma , taken on the heights of the Serra, and 
in this species the male bears, on the blue-black upper surface of the hind¬ 
wing, an oval, ochre-yellow brand, intersected by the discoidal, and behind 
it in the cell a long pencil of dull yellow hairs, which the insect can erect 
and expand at will. In the males of many species of Theda there is on 
the upper surface of the fore-wing, near the apex of the cell a generally 
dark-coloured patch, formed by abnormally shaped, very firmly fixed 
scales: in the larger species one can usually detect a scent emanating 
from this patch. In the splendid Theda atys it is very strong, so as to 
be noticeable as soon as one has the creature in the net, and withal 
disagreeable and bat-like. 
All these and other scent-organs have this in common, that as long as 
the insect is at rest, they are well concealed and protected against evapora¬ 
tion, it may be between the wings, between the wings and abdomen, in 
special grooves, or in pockets formed by a folding over of the margin of 
the wings (as for instance, in the so-called “ costal folds ” of many Hes- 
peridae ), or in the interior of the body, as in the exsertible glands and 
filaments of Morpho and the Glaucopidae. These brushes and manes form 
extremely effective perfume sprinklers, being saturated with the perfume 
when at rest, and then, when suddenly spread out, unfolding an enormous 
surface for evaporation. 
One is fully justified in attributing the same significance to all these 
similar contrivances, so widely spread among the Lepidoptera, even where 
no scent has as yet been detected, and even if such is actually not per¬ 
ceptible to the human olfactory organs. 
Naturally these extremely diverse types of scent apparatus did not 
suddenly appear in their present perfection, but must have been developed 
from more simple conditions. And inasmuch as many of these are com¬ 
paratively recent developments, as is proved by their widely different 
structure in closely allied genera, or even within the same genus ( e.g . 
Papilio), the hope that we may yet discover such simpler conditions is not 
wholly unjustified. Since sometimes even well-developed scent-patches (as 
in Gallidryas philea 1 male) or hair-tufts ( Mechanitis lysimnia male) do not 
distribute any perfume perceptible to us, it is natural that one must from 
the first give up all hope of detecting such simple forms by means of the 
nose, and must ascertain their significance in some other manner. And 
it can, as a matter of fact, be demonstrated, that there are on the wings of 
various butterflies scale structures, which can with great probability be 
regarded as simple, original scent-organs. Among these the scent-scales 
1 See, however, the terminal note on p, 615.—Jil.B.P, 
