84 



Appendices to Fourth Annual Report 



dorsal fin anterior to the centre of the body length (though not to such a 

 decisive degree as its backward position appears among those of summer), 

 yet, when taken relatively to the total length, its position in the majority 

 of examples is posterior to that point ; the explanation would appear to 

 again lie in the fact that, in the latter case, the centre point will be brought 

 forward, i.e.^ the fin will apparently go back in position, and this will be 

 strongly emphasised by the fact that most of these winter fish — a con- 

 siderably larger proportion than of the summer — have the head longer 

 than the caudal fin behind the scales. The greater change of position of 

 the fin among the winter fish in the two tables than among those of sum- 

 mer will be partly also increased by the circumstance formerly noticed, 

 that the head of the winter is rather larger than that of the summer her- 

 ring. According to either table, however, there is a larger proportion of 

 summer fish with the centre of the dorsal fin behind the body centre than 

 of those of winter. It must be remembered, however, that so many fish 

 of both winter and summer seasons cover the same ground of variation, 

 that in itself this could only be trusted to as a means of distinguishing 

 the one from the other in the case of a large number. 



The tables of immature fish show us that among both the winter and 

 summer herrings the fin centre is generally anterior to the centre of the 

 body length and of the total length ; this being much more pronounced 

 among the immature herrings caught in winter than among those taken in 

 summer. The head of the immature herring is relatively larger than that 

 of the mature, for which reason the dorsal fin would appear further 

 forward among them as relative to the total length, but we must notice 

 also, in comparing these tables, that the winter immature fish were gene- 

 rally shorter than those caught in summer, in consequence of which the 

 percentage of winter immatures with the dorsal fin in the most anterior 

 position is likely to be greater than that of the summer immatures. It 

 appears, however, that as the herring grows, the centre of the length of 

 body comes forward, or in other words there is a greater increase in length 

 between the centre of the dorsal fin and the head, than between that 

 point and the tail. 



An examination of the position of the first ray of the dorsal fin need not 

 be entered into fully since the length of the fin, to be afterwards referred 

 to, is the only condition of variation affecting its position beyond what is 

 shown by its centre ; but it may be noted that in general, as stated above 

 for the centre, the first ray position covers, among the winter fish, a larger 

 range of variation, especially in a forward direction, than does that of the 

 summer fish, and as a consequence of this, the percentage of herrings with 

 the fin anterior to the centre of body is much greater among the winter 

 than among the summer fish. 



Table XIV. scarcely requires explanation. It shows again the prevalence 

 of the dorsal fin centre anterior to centre of body among the winter herrings. 

 The division representing the most anterior fin position contains herrings 

 from every locality. That indicating those with a backwardly placed fin 

 contains fish from such widely separated districts, — as Girvan^ Helmsdale, 

 and Anstruther, — that we can scarcely on that ground alone be justified 

 in altogether excluding the others without further corroborating proof. 



The columns containing the results, as regards the centre of body, must 

 not be read too strictly, but subject to the correction of the table of pro- 

 portions, as, for instance, in the case of Lybster, where two-thirds of the 

 herrings are shown as having the fin anteriorly placed. The real position 

 of half of those that fall under this heading was really so close to the 

 centre, that practically they might have been placed in that category, and 

 would have shown a considerably different, perhaps truer, result. More- 



