262 
SEXUAL SELECTION: MAMMALS. 
Part IL, 
bitclies both in weight and size. At birth, and for 
several weeks afterwards, a bitch-pnppy will occa- 
“ sionally be larger than any of the dogs, but they are 
invariably beaten by them later.” Mr. McNeill, of 
Colinsay, concludes that ‘^the males do not attain 
their full growth till over two years old, though 
^^the females attain it sooner.” According to Mr. 
Guppies’ experience, male dogs go on growing in 
stature till they are from twelve to eighteen months 
old, and in weight till from eighteen to twenty-four 
months old; whilst the females cease increasing in 
stature at the age of from nine to fourteen or fifteen 
months, and in weight at the age of from twelve to 
fifteen months. From these various statements it is 
clear that the full difierence in size between the 
male and female Scotch deer-hound is not acquired 
until rather late in life. The males are almost exclu- 
sively used for coursing, for, as Mr. McNeill informs 
me, the females have not sufficient strength and weight 
to pull down a full-grown deer. From the names used 
in old legends, it appears, as I hear from Mr. Guppies,, 
that at a very ancient period the males were the most 
celebrated, the females being mentioned only as the 
mothers of famous dogs. Hence during many genera- 
tions, it is the male which has been chiefly tested 
for strength, size, speed, and courage, and the best 
will have been bred from. As, however, the males 
do not attain their full dimensions until a rather 
late period in life,^ they will have tended, in ac- 
cordance with the law often indicated, to transmit 
their characters to their male offspring alone ; and 
thus the great inequality in size between the sexes 
of the Scotch deer-hound may probably be accounted 
for. 
The males of some few quadrupeds possess organs or 
