length and in actual capacity, in
comparison with the skulls of wild English rabbits. But when we compare
the capacities of the skull in the three Porto Santo rabbits, we
observe a surprising difference, which does not stand in any relation
to the slight difference in the length of their skulls, nor, as I
believe, to any difference in the size of their bodies; but I neglected
to weigh separately their bodies. I can hardly suppose that the
medullary matter of the brain in these three rabbits, living under
similar conditions, can differ as much as is indicated by the
proportional difference of capacity in their skulls; nor do I know
whether it is possible that one brain may contain considerably more
fluid than another. Hence I can throw no light on this case.

Looking to the lower half of the Table, which gives the measurements of
domesticated rabbits, we see that in all the capacity of the skull is
less, but in very various degrees, than might have been anticipated
according to the length of their skulls, relatively to that of the wild
rabbit No. 1. In line 22 the average measurements of seven large
lop-eared rabbits are given. Now the question arises, has the average
capacity of the skull in these seven large rabbits increased as much as
might have been expected from their greatly increased size of body. We
may endeavour to answer this question in two ways: in the upper half of
the Table we have measurements of the skulls of six small wild rabbits
(Nos. 5 to 10), and we find that on an average the skulls are in length
.18 of an inch shorter, and in capacity 91 grains less, than the
average length and capacity of the three first wild rabbits on the
list. The seven large lop-cared rabbits, on an average, have skulls
4.11 inches in length, and 1136 grains in capacity; so that these
skulls have increased in length more than five times as much as the
skulls of the six small wild rabbits have decreased in length; hence we
might have expected that the skulls of the large lop-eared rabbits
would have increased in capacity five times as much as the skulls of
the six small rabbits have decreased in capacity; and this would have
given an average increased capacity of 455 grains, whilst the real
average increase is only 155 grains. Again, the large lop-eared rabbits
have bodies of nearly the same wei