POSTSCRIPT. 
VoL. I. pp. 297-299, — I have fallen into a serious and 
unfortunate error, in relation to the sexual differences 
of animals, in attempting to explain what seemed to 
me a singular coincidence in the late period of life 
at which the necessary variations have arisen in many 
cases, and the late period at which sexual selection 
acts. The explanation given is wholly erroneous, as 
I have discovered by working out an illustration in 
figures. Moreover, the supposed coincidence of period 
is far from general, and is not remarkable ; for, as I 
have elsewhere attempted to show, variations arising 
early in life have often been accumulated through 
sexual selection, being then commonly transmitted to 
both sexes. On the other hand, variations arising late 
in life cannot fail to coincide approximately in period 
with that of the process of sexual selection. Allusions 
to these erroneous views reappear in VoL II. pp. 161 
and 237. 
