The number is uniform in all the skeletons which I have examined, with two exceptions, namely, in one of the small feral Porto Santo rabbits and in one of the largest lop-eared kinds; both of these had as usual seven cervical, twelve dorsal with ribs, but, instead of seven lumbar, both had eight lumbar vertebrae. This is remarkable, as Gervais gives seven as the number for the whole genus Lepus. The caudal vertebrae apparently differ by two or three, but I did not attend to them, and they are difficult to count with certainty.
(FIGURE 12. ATLAS VERTEBRAE, of natural size; inferior surface viewed obliquely. Upper figure, Wild Rabbit. Lower figure, Hare-coloured, large, Lop-eared Rabbit, a, supra-median, atlantoid process; b, infra-median process.)
In the first cervical vertebra, or atlas, the anterior margin of the neural arch varies a little in wild specimens, being either nearly smooth, or furnished with a small supra-median atlantoid process; I have figured a specimen with the largest process (a) which I have seen; but it will be observed how inferior this is in size and different in shape to that in a large lop-eared rabbit. In the latter, the infra-median process (b) is also proportionally much thicker and longer. The alae are a little squarer in outline.
(FIGURE 13. THIRD CERVICAL VERTEBRAE, of natural size, of: A. Wild Rabbit; B. Hare-coloured, large, Lop-eared Rabbit, a, a, inferior surface; b, b, anterior articular surfaces.)
THIRD CERVICAL VERTEBRA.
In the wild rabbit (figure 13, A a) this vertebra, viewed on the inferior surface, has a transverse process, which is directed obliquely backwards, and consists of a single pointed bar; in the fourth vertebra this process is slightly forked in the middle. In the large lop-eared rabbits this process (B a) is forked in the third vertebra, as in the fourth of the wild rabbit. But the third cervical vertebrae of the wild and lop-eared (A b, B b) rabbits differ more conspicuously when their anterior articular surfaces are compared; for the extremities of the antero-dorsal processes in the wild rabbit are simply rounded, whilst in the lop-eared they are trifid, with a deep central pit. The canal for the spinal marrow in the lop-eared (B b) is more elongated in a transverse direction than in the wild rabbit; and the passages for the arteries are of a slightly different shape. These several differences in this vertebra seem to me well deserving attention.
FIRST DORSAL VERTEBRA.
Its neural spine varies in length in the wild rabbit; being sometimes very short, but generally more than half as long as that of the second dorsal; but I have seen it in two large lop-eared rabbits three-fourths of the length of that of the second dorsal vertebra.
(FIGURE 14. DORSAL VERTEBRAE, from sixth to tenth inclusive, of natural size, viewed laterally. A. Wild Rabbit. B. Large, Hare-coloured, so called Spanish Rabbit.)