Fig. 16—Acromion of Scapula, of natural size. A. Wild Rabbit. B, C, D, Large, Lop-eared Rabbits.

Scapula.—The acromion sends out a rectangular bar, ending in an oblique knob, which latter in the wild rabbit (fig. 16, A) varies a little in shape and size, as does the apex of the acromion in sharpness, and the part just below the rectangular bar in breadth. But the variations in these respects in the wild rabbit are very slight: whilst in the large lop-eared rabbits they are considerable. Thus in some specimens (B) the oblique terminal knob is developed into a short bar, forming an obtuse angle with the rectangular bar. In another specimen (C) these two unequal bars form nearly a straight line. The apex of the acromion varies much in breadth and sharpness, as may be seen by comparing figures B, C, and D.

Limbs.—In these I could detect no variation; but the bones of the feet were too troublesome to compare with much care.

I have now described all the differences in the skeletons which I have observed. It is impossible not to be struck with the high degree of variability or plasticity of many of the bones. We see how erroneous the often-repeated statement is, that only the crests of the bones which give attachment to muscles vary in shape, and that only parts of slight importance become modified under domestication. No one will say, for instance, that the occipital foramen, or the atlas, or the third cervical vertebra is a part of slight importance. If the several vertebræ of the wild and lop-eared rabbits, of which figures have been given, had been found fossil, palæontologists 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 length 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 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 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 rabbits. If we had possessed a large number of domesticated rabbits of nearly the same size with the wild rabbits, it would have been a simple task to have measured and compared the capacities of their skulls. But this is not the case: almost all the domestic breeds have larger bodies than wild rabbits, and the lop-eared kinds are more than double their weight. As a small animal has to exert its senses, intellect, and instincts equally with a large animal, we ought not by any means to expect an animal twice or thrice as large as another to have a brain of double or treble the size.[[27]] Now, after weighing the bodies of four wild rabbits, and of four large but not fattened lop-eared rabbits, I find that on an average the wild are to the lop-eared in weight as 1 to 2·17; in average length of body as 1 to 1·41; whilst in capacity of skull they are as 1 to 1·15. Hence we see that the capacity of the skull, and consequently the size of the brain, has increased but little, relatively to the increased size of the body; and this fact explains the narrowness of the skull relatively to its length in all domestic rabbits.

IIIIIIIV
Name of Breed
WILD AND SEMI-WILD RABBITS.		Length of
Skull.		Length of
Body from
Incisors
to Anus.		Weight
of whole
Body.		Capacity
of Skull
measured
by Small
Shot.
inchesincheslbs ozsgrains
1Wild Rabbit, Kent3·1517·43 5 972
2Wild Rabbit, Shetland Islands3·15—— 979
3Wild Rabbit, Ireland3·15—— 992
4Domestic rabbit, run wild, Sandon3·1518·5— 997
5Wild, common variety, small specimen, Kent2·9617·02 14 875
6Wild, fawn-coloured variety, Scotland3·10—— 918
7Silver-grey, small specimen, Thetford warren2·9515·52 11 938
8Feral rabbit, Porto Santo2·83—— 893
9Feral rabbit, Porto Santo2·85—— 756
10Feral Rabbit, Porto Santo2·95—— 835
Average of the three Porto Santo rabbits2·88—— 828
DOMESTIC RABBITS.
11Himalayan3·5020·5— 963
12Moscow3·2517·03 8 803
13Angora3·5019·53 1 697
14Chinchilla3·6522·0— 995
15Large lop-eared4·1024·57 01065
16Large lop-eared4·1025·07 131153
17Large lop-eared4·07——1037
18Large lop-eared4·1025·07 41208
19Large lop-eared4·30——1232
20Large lop-eared4·25——1124
21Large hare-coloured3·8624·06 141131
22Average of above seven large lop-eared rabbits4·11 24·627 41136
23Hare (L. timidus) English specimen3·61—7 01315
24Hare (L. timidus) German specimen3·82—7 01415
VVIVII
Name of Breed
WILD AND SEMI-WILD RABBITS.		Capacity
calculated
according to
Length of Skull
relatively
to that of
No. 1.		Difference
between
actual and
calculated
capacities
of Skulls.		Showing how much
per cent. the Brain,
by calculation
according to the
length of the Skull
is too light or too
heavy, relatively
to the Brain of the
Wild Rabbit No. 1.
grainsgrains
1Wild Rabbit, Kent——
2Wild Rabbit, Shetland Islands——2 per cent. too heavy
in comparison with No. 1
3Wild Rabbit, Ireland——
4Domestic rabbit, run wild, Sandon
5Wild, common variety, small specimen, Kent 913 384 per cent. too light.
6Wild, fawn-coloured variety, Scotland 950 323 per cent. too light.
7Silver-grey, small specimen, Thetford warren 910 283 per cent. too heavy.
8Feral rabbit, Porto Santo 873 202 per cent. too heavy.
9Feral rabbit, Porto Santo 87912316 per cent. too light.
10Feral Rabbit, Porto Santo 910 759 per cent. too light.
Average of the three Porto Santo rabbits 888 607 per cent. too light.
DOMESTIC RABBITS.
11Himalayan108011712 per cent. too light.
12Moscow100219924 per cent. too light.
13Angora108038354 per cent. too light.
14Chinchilla112613113 per cent. too light.
15Large lop-eared126520018 per cent. too light.
16Large lop-eared12651129 per cent. too light.
17Large lop-eared125521821 per cent. too light.
18Large lop-eared1265 574 per cent. too light.
19Large lop-eared1326 947 per cent. too light.
20Large lop-eared131118716 per cent. too light.
21Large hare-coloured1191 605 per cent. too light.
22Average of above seven large lop-eared rabbits126813211 per cent. too light.

In the upper half of Table 3 I have given the measurements of the skull of ten wild rabbits; and in the lower half, of eleven thoroughly domesticated kinds. As these rabbits differ so greatly in size, it is necessary to have some standard by which to compare the capacities of their skulls. I have selected the length of skull as the best standard, for in the larger rabbits it has not, as already stated, increased in length so much as the body; but as the skull, like every other part, varies in length, neither it nor any other part affords a perfect standard.