Chap. IV. 



DIFFEEENCES IN THEIR SKELETONS. 



119 



larger and larger ears. The influence of the external ear on the bony 

 meatus is well shown in the skulls (I have examined three) of half-lops 

 (see fig 5) in which one ear stands upright, and the other and longer 

 ear hangs down ; for in these skulls there was a plain difference in the form 

 and direction of the bony meatus on the two sides. But it is a much more 

 interesting fact, that the changed direction and increased size of the bony 

 meatus have slightly affected on the same side the structure of the whole 

 skull. I here give a drawing of the skull of a half-lop; and it may be 

 observed that the suture between 

 the parietal and frontal bones does 

 not run strictly at right angles 

 to the longitudinal axis of the 

 skull; the left frontal bone pro- 

 jects beyond the right one; both 

 the posterior and anterior margins 

 of the left zygomatic arch on the 

 side of the lopping ear stand a 

 little in advance of the correspond- 

 ing bones on the opposite side. 

 Even the lower jaw is affected, and 

 the condyles are not quite sym- 

 metrical, that on the left standing 

 a little in advance of that on the 

 right. This seems to me a remark- 

 able case of correlation of growth. 

 Who would have surmised that by 

 keeping an animal during many 

 generations under confinement, and 

 so leading to the disuse of the 

 muscles of the ears, and by con- 

 tinually 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 proportionally a little longer. The 

 molar teeth have increased in size proportionally 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 



Fig. 11— Skull, of natural size, of Half-lop Rabbit, 

 showing the different direction of the auditory 

 meatus on the two sides, and the consequent ge- 

 neral distortion of the skull. The left ear of the 

 animal (or right side of figure) lopped forwards. 



