52 THE SCOTTISH NATURALIST 



owned in common by the neighbouring crofters, who said 

 they had been there a long time, but no one knew their 

 origin. He procured a ram (PL III., Fig. 3) and two ewes, 

 which soon increased. Average carcase weight in good con- 

 dition, 20 lbs. Tail quite short and hardly apparent. Wool 

 jet-black and short. Remained fertile to a great age ; a pair 

 kept from the rest had twins at ten years old. A Cheviot 

 ewe crossed with one of these sheep had a lamb with silver- 

 grey fleece, but no other effect was produced and no increase 

 of size. The next cross was a small black sheep said to have 

 come from Caithness and to be of the same breed. The 

 next cross was a four-horned " St Kilda " ram ; this had no 

 immediate effect ; in the next generation four horns appeared 

 in both sexes ; size and shape remained practically unaltered. 

 The next addition was a ram and two ewes of small black 

 sheep from the Orkneys, almost exactly like the Rockies ; 

 there were now twenty-eight in all, and the flock was kept 

 at this number for three years without any apparent change, 

 except in the horns ; some of the rams and ewes had four, 

 and some retained the original two horns. In 1906 they 

 were put into a large field where they had much more room ; 

 the effect of this was very good, both in the greater increase 

 and in the variation in the horns; the number jumped up 

 from about twenty-eight to forty-six. Since then there has 

 been no great increase. He then discusses the origin of 

 these sheep, which he supposes to be the remains of the 

 original breed of the country, and which Walker supposed 

 were introduced by the Norwegians in the ninth century, and 

 to have been isolated on these cliffs from the Cheviot and 

 Black-faced sheep, with which his flock have a disinclination 

 to breed. He thinks them to be a representative of Ovis 

 studeri, but, from the horns of the original ram (PL III., 

 Fig. 3), Ewart believes the Rocky sheep are more intimately 

 related to a race of the Black-faced type than to one of the 

 Mouflon or Soay type. 1 



1 For the figures of the Soay ram (PL I. and PI. III., Fig. 2) and the 

 figure of the N. Ronaldshay ram (PL III., Fig. 1) the author is indebted 

 to Prof. Ewart. 



