Chap. III. CAUSES OF VARIATION. 91 



well do, as their lips do not join, and hence they are found to 

 perish before the common cattle. This strikes me as a good 

 illustration of how little we are able to judge from the ordinary 

 habits of an animal, on what circumstances, occurring only at 

 long intervals of time, its rarity or extinction may depend. It 

 shows us, also, how natural selection would have determined 

 the rejection of the niata modification had it arisen in a state 

 of nature. 



Having described the semi-monstrous niata breed, I may 

 allude to a white bull, said to have been brought from Africa, 

 which was exhibited in London in 1829, and which has been 

 well figured by Mr. Harvey. 67 It had a hump, and was fur- 

 nished with a mane. The dewlap was peculiar, being divided 

 between its fore-legs into parallel divisions. Its lateral hoofs 

 were annually shed, and grew to the length of five or six inches. 

 The* eye was very peculiar, being remarkably prominent, and 

 "resembled a cup and ball, thus enabling the animal to see 

 on all sides with equal ease ; the pupil was small and oval, or 

 rather a parallelogram with the ends cut off, and lying trans- 

 versely across the ball." A new and strange breed might 

 probably have been formed by careful breeding and selection 

 from this animal. 



I have often speculated on the probable causes through 

 which each separate district in Great Britain came to possess 

 in former times its own peculiar breed of cattle ; and the ques- 

 tion is, perhaps, even more perplexing in the case of Southern 

 Africa. We now know that the differences may be in part attri- 

 buted to descent from distinct species ; but this will not suffice. 

 Have the slight differences in climate and in the nature of the 

 pasture, in the different districts of Britain, directly induced 

 corresponding differences in the cattle? We have seen that 

 the semi-wild cattle in the several British parks are not identical 

 in colouring or size, and that some degree of selection has been 

 requisite to keep them true. It is almost certain that abundant 

 food given during many generations directly affects the size of 

 a breed. 68 That climate directly affects the thickness of the 



6 7 Loudon's < Magazine of Nat. Hist.,' and dewlap, 

 vol. I, 1829, p. 113. Separate figures es Low , < Domesticated Animals of 



are given of the animal, its hoofs, eye, the British Isles,' p. 264. 



