This last remark deserves attention, as bearing on the question whether
bright colours are serviceable to male animals from being ornamental.
In one genus of sloths, it is now established, as Dr. Gray states,
that the males are ornamented differently from the females that is to
say, that they have a patch of soft short hair between the shoulders,
which is generally of a more or less orange colour, and in one species
pure white. The females, on the contrary, are destitute of this mark.
The terrestrial Carnivora and Insectivora rarely exhibit sexual
differences of any kind, including colour. The ocelot (Felis pardalis),
however, is exceptional, for the colours of the female, compared with
those of the male, are moins apparentes, le fauve, etant plus terne,
le blanc moins pur, les raies ayant moins de largeur et les taches
moins de diametre. (22. Desmarest, Mammalogie, 1820, p. 220. On
Felis mitis, Rengger, ibid. s. 194.) The sexes of the allied Felis
mitis also differ, but in a less degree; the general hues of the female
being rather paler than in the male, with the spots less black. The
marine Carnivora or seals, on the other hand, sometimes differ
considerably in colour, and they present, as we have already seen,
other remarkable sexual differences. Thus the male of the Otaria
nigrescens of the southern hemisphere is of a rich brown shade above;
whilst the female, who acquires her adult tints earlier in life than
the male, is dark-grey above, the young of both sexes being of a deep
chocolate colour. The male of the northern Phoca groenlandica is tawny
grey, with a curious saddle-shaped dark mark on the back; the female is
much smaller, and has a very different appearance, being dull white or
yellowish straw-colour, with a tawny hue on the back ; the young at
first are pure white, and can hardly be distinguished among the icy
hummocks and snow, their colour thus acting as a protection. (23. Dr.
Murie on the Otaria, Proceedings Zoological Society, 1869, p. 108.
Mr. R. Brown on the P. groenlandica, ibid. 1868, p. 417. See also on
the colours of seals, Desmarest, ibid. pp. 243, 249.)
With Ruminants sexual differences of colour occur more commonly than in
any other order. A difference of this kind is general in the
Strepsicerene antelopes; thus the male nilghau (Portax picta) is
bluish-grey and much darker than the female, with the square white
patch on the throat, the white marks on the fetlocks, and the black
spots on the ears all much more distinct. We have seen that in this
species the crests and tufts of hair are likewise more developed in the
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