CHAP. IV, DIFFERENCES IN THEIR SKELETONS. 125 



an animal during many generations under confinement, and so 

 leading to the disuse of the muscles of the ears, and by continually 

 selecting individuals with the longest and largest ears, he would 

 thus indirectly have affected almost every suture in the skull and 

 the form of the lower jaw ! 



In the large lop-eared rabbits the only difference in the lower 

 jaw, in comparison with that of the wild rabbit, is that the posterior 

 margin of the ascending ramus is broader and more inflected. The 

 teeth in neither jaw present any difference, except that the small 

 incisors, beneath the large ones, are proportionately a little longer. 

 The molar teeth have increased in size proportionately with the 

 increased width of the skull, measured across the zygomatic arch, 

 and not proportionally with its increased length. The inner line of 

 the sockets of the molar teeth in the upper jaw of the wild rabbit 

 forms a perfectly straight line ; but in some of the largest skulls of 

 the lop-eared this line was plainly bowed inwards. In one specimen 

 there was an additional molar tooth on each side of the upper jaw, 

 between the molars and premolars ; but these two teeth did not 

 correspond in size ; and as no rodent has seven molars, this is 

 merely a monstrosity, though a curious one. 



The five other skulls of common domestic rabbits, some of which 

 approach in size the above-described largest skulls, whilst the 

 others exceed but little those of the wild rabbit, are only worth 

 notice as presenting a perfect gradation in all the above-specified 

 differences between the skulls of the largest lop-eared and wild 

 rabbits. In all, however, the supra-orbital plates are rather larger, 

 and in all the auditory meatus is larger, in conformity with the 

 increased size of the external ears, than in the wild rabbit. The 

 lower notch in the occipital foramen in some was not so deep as in 

 the wild rabbit, but in all five skulls the upper notch was well 

 developed. 



The skull of the Angora rabbit, like the latter five skulls, is inter- 

 mediate in general proportions, and in most other characters, between 

 those of the largest lop-eared and wild rabbits. It presents only 

 one singular character : though considerably longer than the skull 

 of the wild rabbit, the breadth measured within the posterior supra- 

 orbital fissures is nearly a third less than in the wild. The skulls 

 of the silver-grey, and chinchilla and Himalayan rabbits are more 

 elongated than in the wild, with broader supra-orbital plates, but 

 differ little in any other respect, excepting that the upper and lower 

 notches of the occipital foramen are not so deep or so well developed. 

 The skull of the Moscow rabbit scarcely differs at all from that of the 

 wild rabbit. In the Porto Santo feral rabbits the supra-orbital plates 

 are generally narrower and more pointed than in our wild rabbits. 



As some of the largest lop-eared rabbits of which I prepared 

 skeletons were coloured almost like hares, and as these latter animals 

 and rabbits have, as it is affirmed, been recently crossed in France, 

 it might be thought that some of the above-described characters 

 had been derived from a cross at a remote period with the hare. 



