occipital foramen, or the atlas, or the third cervical
vertebra is a part of slight importance. If the several vertebrae of the
wild and lop-eared rabbits, of which figures have been given, had been
found fossil, palaeontologists would have declared without hesitation that
they had belonged to distinct species.

_The effects of the use and disuse of parts._--In the large lop-eared
rabbits the relative proportional lengths of the bones of the same leg,
and of the front and hind legs compared with each other, have remained
nearly the same as in the wild rabbit; but in weight, the bones of the
hind legs apparently have not increased in due proportion with the
front legs. The weight of the whole body in the large rabbits examined
by me was from twice to twice and a half as great as that of the wild
rabbit; and the weight of the bones of the front and hind limbs taken
together (excluding the feet, on account of the difficulty of perfectly
cleaning so many small bones) has increased in the large lop-eared
rabbits in nearly the same proportion; consequently in due proportion
to the weight of body which they have to support. If we take the length
of the body as the standard of comparison, the limbs of the large
rabbits have not increased in length in due proportion by one inch, or
by one inch and a half. Again, if we take as the standard of comparison
the length of the skull, which, as we have before seen, has not
increased in length in due proportion to the length of body, the limbs
will be found to be, proportionally with those of the wild rabbit, from
half to three-quarters of an inch too short. Hence, whatever standard
of comparison be taken, the limb-bones of the large lop-eared rabbits
have not increased in length, though they have in weight, in full
proportion to the other parts of the frame; and this, I presume, may be
accounted for by the inactive life which during many generations they
have spent. Nor has the scapula increased in length in due proportion
to the increased length of the body.

The capacity of the osseous case of the brain is a more interesting
point, to which I was led to attend by finding, as previously stated,
that with all domesticated rabbits the length of the skull relatively
to its breadth has greatly increased in comparison with that of the
wild rabbit. If we had possessed a larg