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APPENDIX 
at the apex of the abdomen a partially retractile bunch of hair. Similarly 
among the Pierinae. Here, too, there are species—one at least is known 
to me—in which the scent originates, not in the wings, but from the apex 
of the abdomen. The male of Daptonoura ilaire possesses on the ventral 
surface, just anterior to the anal valvulae, a non-retractile brush of hair, 
about 4 mm. in length. The brush when at rest, is closely pressed to the 
ventral margin of the anal valvulae, extending slightly beyond them. By 
pressing the abdomen it can be spread out on all sides, and then emits a 
very distinct, though feeble scent. I have never taken the female of this 
species, but do not doubt that the brush of hair occurs only in the male, 
and that the scent serves to attract the opposite sex, and not as a warning 
to foes. Scents which serve this latter purpose are usually given off 
instinctively by the insect as soon as it is captured. Thus the females of 
various “ Maracuja butterflies ” (Heliconius, Eueides , Golaenis , Agraulis) 
when seized, protrude from between the seventh and eighth dorsal plates 
two fleshy glands, which meet along the middle dorsal line, and exhale a 
more or less penetrating scent, while the male, under similar circumstances, 
separates the anal valvulae, on the inner side of which similar glands are 
situated. If one catches a male of Didonis biblis, it protrudes on the 
dorsal surface, between the fourth and fifth segments, two roundish bodies, 
meeting along the centre line, covered with short grey hairs and emitting 
a scent: pressing the abdomen causes the protrusion of two similar bodies 
between the fifth and sixth segments; these are beset with longer white 
hairs, which on protrusion radiate in all directions. I regret that I have 
not been able to ascertain whether such glands exist in the female. 
The Ithomiae of the Amazon, which have been made so celebrated by 
Bates as the models for Leptalis and other mimicking Lepidoptera of that 
locality, are said to be protected against birds by a disagreable scent. Is 
this the same scent as that emitted by the closely allied Dircenna xantlio , and 
is it emitted by the hair-tufts of the males ? If that were so, one could 
understand the hundred-fold predominance of the males recorded by Bates, 
and the entire correspondence between the sexes in pattern and colour. 
If the possession of a scent repulsive to pursuers were confined to the 
males, and the sexes in equal numbers, then their enemies would secure a 
palatable mouthful just as often as a disagreeable one, and would scarcely 
be induced to give up the capture of Ithomiae. But this would follow the 
more surely according as the males predominated, and the less often the 
chase resulted in an agreeable morsel. Again, the females, being indis¬ 
tinguishable from the males, would, although wanting the protective 
scent, share in the security which the males owe to their tufts. Hence, in 
this case, the similar coloration of the sexes confers upon the female a 
protective resemblance, established and maintained by natural selection, as 
in the mimicking Leptalis. 
I close with the hope that investigators who have access to rich 
collections will give us further information regarding the distribution of 
