26 
SOUTH-AFEICAN BUTTERFLIES. 
pointed. The abdomen of the male is more slender and compact, and 
laterally compressed, while the thorax is relatively larger and thicker. 
The more atrophied condition of the fore-tarsi in the male of three of 
the five Families has been already treated of ; in contrast to those of 
the female, the fore-tarsi are especially noticeable for their imperfect 
development in the male Erycinidm. This sex is also distinguished in 
many genera by various badges on the wings, consisting of a small sac 
(Danais), smooth patches of peculiarly arranged scales {Euplced)^ streaks 
of short appressed hairs along the nervures (Argynnis, some species of 
Papilio), or tufts of hair (Callichyas, Mycalesis)} The prehensile or 
clasping organs at the extremity of the abdomen, although not very 
apparent externally (except in the Fapilionince, where the outer valves 
are conspicuous), are of remarkable development and complexity ; and 
in all cases where the sexes are much alike in general appearance they 
afford with a little pressure a certain means of determining the male.^ 
Many of the Danaina^ (genera Banais, Uuj)lcea, Amauris, Lycorea, Ituna) 
possess, in the same region of the body, a pair of elongate organs 
provided with a dense terminal fascicle of radiating hairs, which do 
not appear to be often exserted, and which I have found only in the 
males. Where there is much difference in colouring, it is almost 
always the male that is the more brilliant in hue, most of the notable 
exceptions being cases in which the female has been modified in pro- 
tective resemblance to some species of another group. In the Danaince, 
the Heliconince, a large number of the Satyrince and NymplialincB, most 
Fapilioninm and some Lyccenidm, the sexes are alike, or differ merely 
in the female being somewhat duller than the male, and the same may 
be said of most of the Hesperidm. Among the Acrceinm, on the con- 
trary, it is rare to find a species whose sexes are alike. It must be 
noted, however, that in the cases of widest dissimilarity between the 
sexes, it is almost invariably only the tipper surface of the wings that 
exhibits so great a contrast, the under surface presenting very slight, 
if any, differences.^ The manifest reason of this is that, with scarcely 
an exception, the colouring of the under side (exposed when the butterfly 
^ These are regarded as scent-organs by Fritz Mtiller and some other observers ; but I 
have not seen proof of this view adduced, and am disposed, with Mr. Bates, to regard them 
as "an outgrowth of the male organisation," without special function. 
^ These accessory male organs have been carefully investigated by Dr. F. Buchanan 
White throughout the European Butterflies, and by Mr. P. H. Gosse in the genus Papilio 
from all parts of the world. In the allied group of TricJioptera, Mr. R. M'Lachlan has 
found in the homologous parts good classificatory characters ; but the astonishing differences 
which they exhibit in closely-allied species of the genus Papilio [e.g., P. Demoleus of Africa 
and P. Erithonius of India, or the African P. Nireus and Bromius) render them apparently 
of little value for systematic arrangement. See Trans. Linn. Soc, ZooL, 2d Series, vol. i. 
p. 357, and vol. ii. p. 265 (1877 and 1883). 
^ This is practically a character of the greatest assistance to the collector and student, 
enabling him to identify the sexes of a species in numberless instances where, if both 
surfaces of the wings had greatly differed, it would have been impossible to arrive at any 
satisfactory conclusion. 
