They vary in colour; but many are symmetrically coloured, being white with a streak along the spine, and with the ears and certain marks about the head of a blackish-grey tint. They have rather longer bodies than common rabbits), a haemal spine was moderately well developed on the under side of the twelfth dorsal vertebra, and I have seen this in no other specimen.
I have stated that in two cases there were eight instead of seven lumbar vertebrae. The third lumbar vertebrae in one skeleton of a wild British rabbit, and in one of the Porto Santo feral rabbits, had a haemal spine; whilst in four skeletons of large lop-eared rabbits, and in the Himalayan rabbit, this same vertebra had a well developed haemal spine.
In four wild specimens this bone was almost absolutely identical in shape; but in several domesticated breeds shades of differences could be distinguished. In the large lop-eared rabbits, the whole upper part of the ilium is straighter, or less splayed outwards, than in the wild rabbit; and the tuberosity on the inner lip of the anterior and upper part of the ilium is proportionally more prominent.
(FIGURE 15. TERMINAL BONE OF STERNUM, of natural size, A. Wild Rabbit. B. Hare-coloured, Lop-eared Rabbit. C. Hare-coloured Spanish Rabbit. (N.B. The left-hand angle of the upper articular extremity of B was broken, and has been accidentally thus represented.))
The posterior end of the posterior sternal bone in the wild rabbit (figure 15, A) is thin and slightly enlarged; in some of the large lop-eared rabbits (B) it is much more enlarged towards the extremity; whilst in other specimens (C) it keeps nearly of the same breadth from end to end, but is much thicker at the extremity.
(FIGURE 16. ACROMION OF SCAPULA, of natural size. A. Wild Rabbit. B, C, D, Large, Lop-eared Rabbits.)
The acromion sends out a rectangular bar, ending in an oblique knob, which latter in the wild rabbit (figure 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.
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 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 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.