320 THE EFFECTS OF CONDITIONS 



classifying the fish according to the number of bars, it 

 was found that, of those in the English Channel and 

 North Sea (including Brest and Scilly), 20 to 22 per 

 cent, had 28 or more bars; of those on the Irish coasts, 

 34 to 38 per cent.; and of those on the American coast, 

 no less than 44 per cent. The proportions of fish hav- 

 ing one or more round black dorso-lateral intermediate 

 spots situated between the transverse bars, showed 

 even more distinct differences. Thus 21 per cent, of 

 the fish from the North Sea and English Channel were 

 spotty; 22 percent, of those from Brest and Scilly; only 

 15 per cent, of those from Ireland; but no less than 66 

 per cent, of those from America. 



It was found that the number of fin-rays in the first 

 dorsal fin varied somewhat according to the size of the 

 fish, it being, for instance, 12.33 in Irish fish under 13 

 inches long, and 11.92 in those of 15 or more inches. 

 To get rid of this variable factor, only fish 13 inches 

 long were compared. Here again the American fish 

 showed the greatest divergence from the general mean, 

 whilst the Brest and Scilly fish were more or less mid- 

 way between the North Sea and Channel fish on the 

 one hand, and the Irish on the other. As regards the 

 second dorsal fin, the variation in the number of fin- 

 rays is much slighter than for the first dorsal fin, it 

 being practically only from 11 to 13 (as against 10 to 

 15). The American fish showed a much wider varia- 

 tion than any of the others, only 63 per cent, of them 

 having the modal number of 12 fin-rays, whilst the two 

 samples of Irish fish showed least variation, 85.3 per 

 cent, and 85.4 per cent, of them respectively having 12 

 fin-rays. In the number of dorsal finlets the American 



