Chap. IV. DIFFERENCES IN THEIK SKELETONS. 



129 



the extremity; whilst in other specimens (o) it keeps nearly of 

 the same breadth from end to end, but is much thicker at the 

 extremity. 



Scapula. — The acromion sends out a rectangular bar, ending in an 

 oblique knob, which latter in the wild rabbit (rig. 16, a) varies a little 

 in shape and size, as does 

 the apex of the acromion in A 



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 de- 

 veloped 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 

 figs, b, c, and d. 



Limbs. — 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 import- 

 ance 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 

 vertebra? 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 



r 



Fig. 16. — Acromion of Scapula, of natural size. 

 A. Wild Rabbit. B, C, D, Large, Lop-eared 

 Babbits. 



