86 



Appendices to Fotirth Annual Report 



over, the reading of the columns of summer fish will often show that 

 where an entry under the heading 'before centre' seems to indicate a 

 majority of fish with fins situated far forward, it may really contain many 

 fish with the fins so near the centre, that they should properly be excluded 

 from the former list. The figures in the table should be taken as approxi- 

 mately rather than absolutely correct. It does not seem possible to find 

 any special law regulating the position of the dorsal fin among the summer 

 herrings, so far as locality is concerned. 



Position of Anal Fin. 



The position of this fin may be considered in two ways, viz., its position 

 on the body of the fish and its position with respect to the dorsal fin. Of 

 course, a comparison of its position on the body with the position of the 

 dorsal fin on the same will give in a general way an idea of its relation to 

 the latter, but only an analysis of the measurements, fish by fish, will 

 inform us to what extent its variation in position is dependent on that of 

 the dorsal. While we may find the general position of the anal fin on the 

 body, and compare it with the general results arrived at regarding the 

 same, character in the case of the dorsal fin, we cannot, without a much 

 more minute analysis of the case in every fish, ascertain how far any 

 special peculiarity in one or the other may be common to both. 



As I have already said, the commencement of the anal fin is close to the 

 vent, and therefore, in finding the position of the first anal ray, we are also 

 ascertaining the position of the vent. 



Using what I have called the common scale for the indication of the 

 ratio of any characteristic to the body length, we find that the position of 

 the anal fin has apparently a very small variation — from 1"21 to 1'35 ; but 

 taking as an index of variation the ratio which it bears to the body length 

 in parts of that dimension, we find that it really extends, like the dorsal, 

 over a considerable range — from '735 to •827. 



Again, as with the other characters, we find these extremes are reached 

 by a comparatively small number of herrings ; a large majority have the 

 fin within the limits — "752 to '785. The winter fish vary rather more in 

 the direction of a forwardly-placed fin than do the summer, viz., '735 to 

 •813; while the summer fish have the advantage in the other direction, 

 varying from '740 to -827. 



Classifying as before, we get the following table of results : — 



TABLE (XV.) showing Percentage of Herrings, arranged according to 

 Position of first Eay of Anal Fin relatively to Length of Body (to 

 end of scales). 





Eatio of Position of Fin. 



•735 



•754 



•773 





•792 



•811 





to 

 •753. 



to 

 •772. 



to 

 •791. 





to 

 •810. 



to 

 •829. 



] 



Vlature 



Winter, 



10-0 



53^0 



33^0 





3^8 



•2 





Fish. 



_ Summer, . 



2-0 



19-0 



46-7 





30^5 



1^8 



Immature 



Winter, : " . 



17-3 



■49-3 



26^6 





5-4 



1^4 



Fish; 



Summer, . 



6-3 



37^5 



40-6 





12-5 



3^1 



. The table represents a similar result to that of Table IX. respecting the 

 dorsal fin. It shows the same excess of percentage of summer herrings 



