and the round black spots on the ears, all more distinct in the male of
the Portax picta, than in the female; when we see that the colours are
more vivid, that the narrow white lines on the flank and the broad
white bar on the shoulder are more distinct in the male Oreas derbyanus
than in the female; when we see a similar difference between the sexes
of the curiously-ornamented Tragelaphus scriptus (Fig. 70), we cannot
believe that differences of this kind are of any service to either sex
in their daily habits of life. It seems a much more probable conclusion
that the various marks were first acquired by the males and their
colours intensified through sexual selection, and then partially
transferred to the females. If this view be admitted, there can be
little doubt that the equally singular colours and marks of many other
antelopes, though common to both sexes, have been gained and
transmitted in a like manner. Both sexes, for instance, of the koodoo
(Strepsiceros kudu) (Fig. 64) have narrow white vertical lines on their
hind flanks, and an elegant angular white mark on their foreheads. Both
sexes in the genus Damalis are very oddly coloured; in D. pygarga the
back and neck are purplish-red, shading on the flanks into black; and
these colours are abruptly separated from the white belly and from a
large white space on the buttocks; the head is still more oddly
coloured, a large oblong white mask, narrowly-edged with black, covers
the face up to the eyes (Fig. 71); there are three white stripes on the
forehead, and the ears are marked with white. The fawns of this species
are of a uniform pale yellowish-brown. In Damalis albifrons the
colouring of the head differs from that in the last species in a single
white stripe replacing the three stripes, and in the ears being almost
wholly white. (38. See the fine plates in A. Smith s Zoology of South
Africa, and Dr. Gray s Gleanings from the Menagerie of Knowsley. )
After having studied to the best of my ability the sexual differences
of animals belonging to all classes, I cannot avoid the conclusion that
the curiously-arranged colours of many antelopes, though common to both
sexes, are the result of sexual selection primarily applied to the
male.
The same conclusion may perhaps be extended to the tiger, one of the
most beautiful animals in the world, the sexes of which cannot be
distinguished by colour, even by the dealers in wild beasts. Mr.
Wallace believes (39. Westminster Review, July 1, 1867, p. 5.) that
the striped coat of the tiger so assimilates with the vertical stems
of the bamboo, as to assist greatly in concealing him from his
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