132 DOMESTIC BABBITS: Ckap IV 



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 weighing 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 measure- 

 ments 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. "\Ve 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 "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, 21) 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.- 3 



23 This standard is apparently con- Zoolog. Soc.,' 1861, p. 86) gives 210 

 Bidfrably too low, for Dr. Crisp ("Proc. grains as the actual weight of the 



