male than in the hornless female. I am informed by Mr. Blyth that the
male, without shedding his hair, periodically becomes darker during the
breeding-season. Young males cannot be distinguished from young females
until about twelve months old; and if the male is emasculated before
this period, he never, according to the same authority, changes colour.
The importance of this latter fact, as evidence that the colouring of
the Portax is of sexual origin, becomes obvious, when we hear (24.
Judge Caton, in Transactions of the Ottawa Academy of Natural
Sciences, 1868, p. 4.) that neither the red summer-coat nor the blue
winter-coat of the Virginian deer is at all affected by emasculation.
With most or all of the highly-ornamented species of Tragelaphus the
males are darker than the hornless females, and their crests of hair
are more fully developed. In the male of that magnificent antelope, the
Derbyan eland, the body is redder, the whole neck much blacker, and the
white band which separates these colours broader than in the female. In
the Cape eland, also, the male is slightly darker than the female. (25.
Dr. Gray, Cat. of Mamm. in Brit. Mus. part iii. 1852, pp. 134-142;
also Dr. Gray, Gleanings from the Menagerie of Knowsley, in which
there is a splendid drawing of the Oreas derbianus: see the text on
Tragelaphus. For the Cape eland (Oreas canna), see Andrew Smith,
Zoology of S. Africa, pl. 41 and 42. There are also many of these
Antelopes in the Zoological Gardens.)
In the Indian black-buck (A. bezoartica), which belongs to another
tribe of antelopes, the male is very dark, almost black; whilst the
hornless female is fawn-coloured. We meet in this species, as Mr. Blyth
informs me, with an exactly similar series of facts, as in the Portax
picta, namely, in the male periodically changing colour during the
breeding-season, in the effects of emasculation on this change, and in
the young of both sexes being indistinguishable from each other. In the
Antilope niger the male is black, the female, as well as the young of
both sexes, being brown; in A. sing-sing the male is much brighter
coloured than the hornless female, and his chest and belly are blacker;
in the male A. caama, the marks and lines which occur on various parts
of the body are black, instead of brown as in the female; in the
brindled gnu (A. gorgon) the colours of the male are nearly the same
as those of the female, only deeper and of a brighter hue. (26. On the
Ant. niger, see Proc. Zool. Soc. 1850, p. 133. With respect to an
allied species, in which there is an equal sexual difference in colour,
see Sir S. Baker, The Albert Nyanza, 1866, vol. ii. p. 627. For the
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