Chap. IV. DIFFERENCES IN THEIR SKELETONS. 121 



Antrim in Ireland. As all the bones in these four specimens from 

 such distant localities closely resembled each other, presenting 

 scarcely any appreciable difference, it may be concluded that the 

 bones of the wild rabbit are generally uniform in character. 



Skull. — I have carefully examined skulls of ten large lop-eared 

 rabbits, and of five common domestic rabbits, which latter differ from 

 the lop-eared only in not having such large bodies or ears, yet both 

 larger than in the wild rabbit. First for the ten lop-eared rabbits : 

 in all these the skull is remarkably elongated in comparison with 

 its breadth. In a wild rabbit the length was 3*15 inches, in a large 

 fancy rabbit 4'3 ; whilst the breadth of the cranium enclosing the 

 brain was in both almost exactly the same. Even by taking as the 

 standard of comparison the widest part of the zygomatic arch, the 

 skulls of the lop-eared are proportionally to their breadth three- 

 quarters of an inch too long. The depth of the head has increased 

 almost in the same proportion with the length ; it is the breadth 

 alone which has not increased. The parietal and occipital bones 

 enclosing the brain are less arched, both in a longitudinal and 

 transverse line, than in the wild rabbit, so that the shape of the 

 cranium is somewhat different. The surface is rougher, less cleanly 

 sculptured, and the lines of sutures are more prominent. 



Although the skulls of the large lop-eared rabbits in comparison 

 with those of the wild rabbit are much elongated relatively to their 

 breadth, yet, relatively to the size of body, they are far from elon- 

 gated. The lop-eared rabbits which I examined were, though not 

 fat, more than twice as heavy as the wild specimens ; but the skull 

 was very far from being twice as long. Even if we take the fairer 

 standard of the length of body, from the nose to the anus, the skull 

 is not on an average as long as it ought to be by a third of an inch. 

 In the small feral Porto Santo rabbit, on the other hand, the head 

 relatively to the length of body is about a quarter of an inch too 

 long. 



This elongation of the skull relatively to its breadth, I find a 

 universal character, not only with the large lop-eared rabbits, but 

 in all the artificial breeds ; as is well seen in the skull of the Angora. 

 I was at first much surprised at the fact, and could not imagine why 

 domestication could produce this uniform result ; but the explana- 

 tion seems to lie in the circumstance that during a number of gene- 

 rations the artificial races have been closely confined, and have had 

 little occasion to exert either their senses, or intellect, or voluntary 

 muscles ; consequently the brain, as we shall presently more fully 

 see, has not increased relatively with the size of body. As the brain 

 has not increased, the bony case enclosing it has not increased, and 

 this has evidently affected through correlation the breadth of the 

 entire skull from end to end. 



In all the skulls of the large lop-eared rabbits, the supra-orbital 

 plates or processes of the frontal bones are much broader than in 

 the wild rabbit, and they generally project more upwards. In the 

 zygomatic arch the posterior or projecting point of the malar-bone 



