368 
SEXUAL SELECTION. 
Paut II. 
generally redder but rather duller than the females, the 
latter being coloured of a more or less splendid golden 
green. On the other hand, in one species the male is 
golden-green, the female being richly tinted with red 
and purple. In the genus Esmeralda the sexes differ so 
greatly in colour that they have been ranked as distinct 
species : in one species both are of a beautiful shining 
green, but the male has a reel thorax. On the whole, 
as far as I could judge, the females of those Prionidse, 
in which the sexes differ, are coloured more richly 
than the males; and this does not accord with the 
common rule in regard to colour when acquired through 
sexual selection. 
Fig. 15. Chalcosoma atlas. Upper figure, male (reduced) ; lower figure, female 
(nat. size). 
trichia and Trichius, the male of the latter being more obscurely 
coloured than the female. In Tillus elongatus the male is black, and 
the female always, as it is believed, of a dark blue colour with a red 
thorax. The male, also, of Orsodacna atra , as I hear from Mr. Walsh, 
is black, the female (the so-called 0. ruficollis ) having a rufous thorax. 
