The Descent of Man

I will first give briefly all the cases known to me
of male quadrupeds differing in colour from
the females. With Marsupials, as I am informed
by Mr. Gould, the sexes rarely differ in this
respect; but the great red kangaroo offers a
striking exception, "delicate blue being the prevailing
tint in those parts of the female which in
the male are red." (19. Osphranter rufus, Gould,
'Mammals of Australia,' 1863, vol. ii. On the
Didelphis, Desmarest, 'Mammalogie,' p. 256.) In
the Didelphis opossum of Cayenne the female
is said to be a little more red than the male. Of
the Rodents, Dr. Gray remarks: "African squirrels,
especially those found in the tropical regions,
have the fur much brighter and more
vivid at some seasons of the year than at others,
and the fur of the male is generally brighter
than that of the female." (20. 'Annals and Magazine
of Natural History,' Nov. 1867, p. 325.
On the Mus minutus, Desmarest, 'Mammalogie,'
p. 304.) Dr. Gray informs me that he specified
the African squirrels, because, from their