282 
SEXUAL selection: mammals. 
Part II. 
when a thin and narrow crest runs along the whole 
length of the back ; for a crest of this kind would 
afford scarcely any protection, and the ridge of the back 
is not a likely place to be injured ; nevertheless such 
crests are sometimes confined to the males, or are 
much more developed in them than in the females. 
Two antelopes, the Tragela^Tius scriptus^^ (see fig. 68, 
p. 300) and Portax picta, may be given as instances. 
The crests of certain stags and of the male wild goat 
stand erect, when these animals are enraged or terri- 
fied;^^ but it can hardly be supposed that they have 
been acquired for the sake of exciting fear in Their 
enemies. One of the above-named antelopes, the Portax 
jpicta, has a large well-defined brush of black hair on 
the throat, and this is much larger in the male than in 
the female. In the Ammotragus tragelaphus of North 
Africa, a member of the sheep-family, the front-legs 
are almost concealed by an extraordinary growth of 
hair, which depends from the neck and upper halves 
of the legs ; but Mr. Bartlett does not believe that this 
mantle is of the least use to the male, in whom it is 
much more developed than in the female. 
Male quadrupeds of many kinds differ from the 
females in having more hair, or hair of a different 
character, on certain parts of their faces. The bull 
alone has curled hair on the forehead. In three 
closely-allied sub-genera of the goat family, the males 
alone possess beards, sometimes of large size; in two 
other sub-genera both sexes have a beard, but this 
Dr. Gray, ‘ Gleanings from the Menagerie at Knowsley,’ pi. 28. 
Judge Caton on the wapiti, ‘ Transact. Ottawa Acad. Nat. 
Sciences,’ 1868, p. 36, 40; Blyth, 'Land and Water,’ on Ca]ora sega- 
grus, 1867, p. 37. 
'Hunter’s Essays and Observations,’ edited by Owen, 1861, vol. i. 
p. 236. 
