y is given which the skull
ought to have had by calculation, according to the length of skull, in
comparison with that of the wild rabbit No. 1; in the sixth column the
difference between the actual and calculated capacities, and in the
seventh the percentage of increase or decrease, are given. For
instance, as the wild rabbit No. 5 has a shorter and lighter body than
the wild rabbit No. 1, we might have expected that its skull would have
had less capacity; the actual capacity, as expressed by the weight of
shot, is 875 grains, which is 97 grains less than that of the first
rabbit. But comparing these two rabbits by the length of their skulls,
we see that in No. 1 the skull is 3.15 inches in length, and in No. 5
2.96 inches in length; according to this ratio, the brain of No. 5
ought to have had a capacity of 913 grains of shot, which is above the
actual capacity, but only by 38 grains. Or, to put the case in another
way (as in column VII), the brain of this small rabbit, No. 5, for
every 100 grains of weight is only 4 per cent. too light,--that is, it
ought, according to the standard rabbit No. 1, to have been 4 per cent.
heavier. I have taken the rabbit No. 1 as the standard of comparison
because, of the skulls having a full average length, this has the least
capacity; so that it is the least favourable to the result which I wish
to show, namely, that the brain in all long-domesticated rabbits has
decreased in size, either actually, or relatively to the length of the
head and body, in comparison with the brain of the wild rabbit. Had I
taken the Irish rabbit, No. 3, as the standard, the following results
would have been somewhat more striking.

Turning to the Table: the first four wild rabbits have skulls of the
same length, and these differ but little in capacity. The Sandon rabbit
{126} (No. 4) is interesting, as, though now wild, it is known to be
descended from a domesticated breed, as is still shown by its peculiar
colouring and longer body; nevertheless the skull has recovered its
normal length and full capacity. The next three rabbits are wild, but
of small size, and they all have skulls with slightly lessened
capacities. The three Porto Santo feral rabbits (Nos. 8 to 10) offer a
perplexing case; their bodies are greatly reduced in size, as in a
lesser degree are their skulls in