126 



DOMESTIC EABBITS. 



Chap. IV 



(No. 4) is interesting, as, though now wild, it is known to be descended 

 from a domesticated breed, as is still shown by its peculiar colouring and 

 longer body ; nevertheless the skull has recovered its normal length and 

 full capacity. The next three rabbits are wild, but of small size, and they 

 all have skulls with slightly lessened capacities. The three Porto Santo 

 feral rabbits (Nos. 8 to 10) offer a perplexing case ; their bodies are greatly 

 reduced in size, as in a lesser degree are their skulls in length and in 

 actual capacity, in comparison with the skulls of wild English rabbits. 

 But when we compare the capacities of the skull in the three Porto Santo 

 rabbits, we observe a surprising difference, which does not stand in any 

 relation to the slight difference in the length of their skulls, nor, as I 

 believe, to any difference in the size of their bodies; but I neglected to 

 weigh separately their bodies. I can hardly suppose that the medullary 

 matter of the brain in these three rabbits, living under similar conditions, 

 can differ as much as is indicated by the proportional difference of capacity 

 in their skulls ; nor do I know whether it is possible that one brain may 

 contain considerably more fluid than another. Hence I can throw no light 

 on this case. 



Looking to the lower half of the Table, which gives the measurements of 

 domesticated rabbits, we see that in all the capacity of the skull is less, 

 but in very various degrees, than might have been anticipated according to 

 the length of their skulls, relatively to that of the wild rabbit No. 1. In 

 line 22 the average measurements of seven large lop-eared rabbits are given. 

 Now the question arises, has the average capacity of the skull in these seven 

 large rabbits increased as much as might have been expected from their 

 greatly increased size of body. We may endeavour to answer this question 

 in two ways : in the upper half of the Table we have measurements of the 

 skulls of six small wild rabbits (Nos. 5 to 10), and we find that on an 

 average the skulls are in length *18 of an inch shorter, and in capacity 

 91 grains less, than the average length and capacity of the three first 

 wild rabbits on the list. The seven large lop-eared rabbits, on an average, 

 have skulls 4'11 inches in length, and 1136 grains in capacity; so that 

 these skulls have increased in length more than five times as much as 

 the skulls of the six small wild rabbits have decreased in length ; hence 

 we might have expected that the skulls of the large lop-eared rabbits 

 would have increased in capacity five times as much as the skulls of the 

 six small rabbits have decreased in capacity ; and this would have given 

 an average increased capacity of 455 grains, whilst the real average increase 

 is only 155 grains. Again, the large lop-eared rabbits have bodies of 

 nearly the same weight and size as the common hare, but their heads are 

 longer ; consequently, if the lop-eared rabbits had been wild, it might have 

 been expected that their skulls would have had nearly the same capacity as 

 that of the skull of the hare. But this is far from being the case ; for the 

 average capacity of the two hare-skulls (Nos. 23, 24) is so much larger than 

 the average capacity of the seven lop-eared skulls, that the latter would 

 have to be increased 21 per cent, to come up to the standard of the hare. 28 



28 This standard is apparently con- 

 siderably too low, for Dr. Crisp (' Proc. 



Zoolog. Soc.,' 1861, p. 86) gives 210 

 grains as the actual weight of the 



