90 



AppeTidices to Fourth Annual Report 



The anal fin varies in length from '087 to "140 in the winter fish, and 

 from "083 to '133 in those of summer. There appears to be no special 

 predominance, as regards either fin, of any particular length over another; 

 nor is there any special distinction between the mature and immature 

 herrings ; but it will be seen that the majority of the winter fish have a 

 narrower range of variation in the dorsal fin length than those of summer. 



The divisions in the table have been arranged to suit both dorsal and 

 anal fins, and facilitate comparison, consequently the percentage of fish 

 with the shorter class of dorsal fin is rather smaller than it should be, in 

 fact the whole dorsal fin percentage is very slightly and unimportantly 

 exaggerated towards the larger extreme of fin length. 



Although so large a percentage of both summer and winter herrings 

 have the dorsal and anal fin lengths in the same columns of the table, it 

 must not be supposed that the combination on one fish of dorsal and anal 

 fins of the same length is common. On the contrary, the dorsal fin is 

 generally longer than the anal. Of the winter herrings examined only 7*5 

 per cent, had the anal fin longer than the dorsal, and scarcely 5 per cent, had 

 it of the same length ; of this quantity 8 per cent, were immature fish. 

 Among the summer fish the percentage was less, only 1 '7 per cent, having 

 the fin longer, while in 6 '5 per cent, the fins were equal; of this quantity 

 5 per cent, were immature. 



It ought to be noticed that all these figures relate to the proportional 

 length of the fin. The difference between the condition in each season, 

 though very small, was slightly in favour of the winter fish having relar 

 tively a shorter dorsal and a longer anal fin than the summer. The aver- 

 age of the absolute length of both dorsal and anal fins was greater among 

 the winter than among the summer herring — a circumstance possibly due 

 only to the rather larger size of the winter fish. 



Fin Mays. 



The number of rays in the dorsal and anal fins does not seem much to 

 affect their basal lengths. The rays of the dorsal fin of the mature summer 

 herring vary in number from 16 to 20, and in the anal fin from 14 to 19. 

 My observations of the number of rays in the fins of the winter herrings are 

 as yet scarcely sufficiently extensive to be altogether trustworthy as an 

 index of the normal condition among the fish of that season, but so far as 

 they go they give no indication of any special distinction in this respect 

 between the herrings of winter and summer. 



Tables XX. and XXI. contain the percentages of summer fish, arranged 

 according to the number of rays in the dorsal and anal fins, and to the 

 absolute length of the fins. 



The pelvic fin is very constant in the number of its rays, being generally 

 composed of nine. Where a variation from this number does exist, it is 

 in many cases a one-sided abnormality. The following are the percent- 

 ages of the herrings examined according to the number of the pelvic fin 

 rays : — 



With 6 rays in one fin, 7 rays in the other, 0*28 per cent. 

 „ 8 „ in both fins, .... 2-00 „ 

 „ 8 „ in one fin, 9 rays in the other, 0*28 „ 

 „ 9 ,, in both fins, . . . 96*3 ,, 

 „ 9 „ in one fin, 10 rays in the other, 0*57 „ 

 „ 10 „ in both fins, . . . 0'57 „ 



100-00 



