of the Fishery Board for Scotland. 



275 



to ascertain what relation the herring of these two seasons bore to one 

 another, whether they were of one and the same stock, so that the summer- 

 herring might be called the younger specimens of the same race of which 

 the winter was the older, or if they were two distinct varieties. After a 

 prolonged and arduous research, Matthews came to the conclusion that 

 the evidence he had, though good, was not suliicient to decide the 

 question. As a matter of fact, his conclusions, as will be shown, tended 

 in favour of the second hypothesis, but because he demanded too much 

 from nature, because the differences did not satisfy his ideal of what was 

 necessary to give two distinct races, he preferred to leave the question 

 unsolved. 



To consider now some of his results ; first, with regard to the length of 

 the head, it was found that the winter-herring had a slightly longer head 

 than those of the summer, but that they vary more than the latter do, and 

 further that the ranges of variation overlapped. A further complica- 

 tion arose when immature herring were considered as well as mature. 

 Immature herring have the head relatively longer than the mature, 

 and the relative size gradually decreases from young stages onwards, 

 so that the largest herring have the smallest proportionate head. 

 If, then, the summer-herring were supposed to be the younger of the 

 same stock as the winter-herring, the head in the latter should be 

 relatively smaller, since they are the older. As a matter of fact the 

 reverse is the case ; the winter-herring are not only somewhat larger in 

 size but have the longer head. 



Again, with regard to the position of the fins, it is shown that in the 

 summer herring the centre of the dorsal fin is behind the body centre, 

 whilst in the winter-herring it is in front. The anal fin, also, is further 

 back (relatively to body length) in the summer- than in the winter-herring, 

 and so again for the pelvics. What has been said above with regard 

 to the head in the immature and mature herrings holds also for the position 

 of the fins. In the young and immature the fins are relatively further 

 forward, and therefore, if the summer-herring are the younger lot of the 

 same race as the winter-herring, the fins ought to be further forward. 

 The reverse again is the case. Moreover, in the winter mature herring 

 the length of the bases of the dorsal and anal fins is relatively greater 

 than the corresponding lengths in the summer-herring. 



We might well ask now why Matthews did not consider these differ- 

 ences sufficient to entitle the summer- and winter-herrings to be called two 

 distinct races, seeing that they even agree with his own criterion — viz., 

 the presence of two or more, not necessarily marked, characters, occurring 

 generally together in the fish of certain localities and at certain seasons. 

 The reasons are as follows : — Firstly, he had not examined all the varying 

 characters, nor did he consider the differences, in the young, and in their 

 habits, in the habits of the adults, nor the differences in their surrounding 

 conditions. Secondly, he considered the differences too small. Thirdly, 

 and this summer most confusing to him, the variations overlapped — i.e., the 

 common ground of variation was the same or nearly the same for both 

 summer- and winter-herring. 



This cannot be gainsaid, and the greater the number of specimens 

 examined, the greater is the possibility of finding this overlapping. Nor 

 could it be otherwise. If the breeds of domestic animals be considered, 

 or if the races of men be compared, it is seen that this overlapping 

 constantly occurs, more especially where the races are closely allied, and 

 yet the races are regarded as distinct. 



It becomes simply a question of how to combine the results so as to 



