]84 
SEXUAL SELECTION: BIKDS. 
Part IL' 
are marked with feeble stripes or rows of spots, and as 
many allied species both young and old are similarly 
marked, no naturalist, who believes in the gradual 
evolution of species, will doubt that the progenitor of 
the lion and puma was a striped animal, the young 
having retained vestiges of the stripes, like the kittens 
of black cats, which when grown up are not in the least- 
striped. Many species of deer, which when mature are 
not spotted, are whilst young covered with white spots,- 
as are likewise some few species in their adult state. 
So again the young in the whole family of pigs (Suidse), 
and in certain rather distantly-allied animals, such as 
the tapir, are marked with dark longitudinal stripes ; 
but here we have a character apparently derived from 
an extinct progenitor, and now preserved by the young 
alone. In all such cases the old have had their colours 
changed in the course of time, whilst the young have 
remained but little altered, and this has been effected 
through the principle of inheritance at corresponding 
ages. 
This same principle applies to many birds belonging 
to various groups, in which the young closely resemble 
each other, and differ much from their respective adult 
parents. The young of almost all the Gallinacem, and 
of some distantly-allied birds such as ostriches, are 
whilst covered with down longitudinally striped ; but 
this character points back to a state of things so re- 
mote that it hardly concerns us. Young cross-bills 
(Loxia) have at first straight beaks like those of other 
finches, and in their immature striated plumage they 
resemble the mature redpole and female siskin, as well 
as the young of the goldfinch, greenfinch, and some 
other allied species. The young, of many kinds of 
buntings (Emberiza) resemble each other, and like- 
wise the adult state of the common bunting, E, 
