HERRING. 
963 
the first measuring 67 — 111 mm. in length of body, 
the second 136 — 201 mm., the third 203 — 240 mm., 
and the fourth containing all the large ^specimens, be- 
tween 242 and 345 mm. in length. The first three 
groups roughly answer, according to other calculations 
of mine, to the age-classes of the first three years. 
Averages in Strommings. 
- 
Number of specimens measured ... 
12 
47 
47 
20 
Length of the body to the end of the caudal lobes, expressed in millimetres 
86 
178.9 
218.5 
253.5 
Distance between the dorsal fin and the tip of the lower jaw in % of the length of the body 
43.8 
44.7 5 
44.07 
44.32 
?? ventral fins , 7 ,, ,, ,, ,, 77 77 ,, ,, 77 ,, ,, ,, ,, ,, 
47.1 
48.93 
48.58 
48.39 
After the second year there thus appears, on an 
average, by no means a backward removal, but a re- 
gular advancement both of the dorsal and the ventral 
fins. The normal development of the Stromming, in 
accordance with the rules for the Herring-type, termi- 
nates in general at- the end of the second year. And 
it then shows, as we have seen above (the table on 
p. 961, relation no. 8), at an average length of 203 
mm., the same position of the ventral fins as the Nor- 
wegian Herring does at a length of 170 mm. As re- 
gards the position of the dorsal fin (relation no. 5), the 
same rule applies to the Bohuslan Herrings. 
That a racial difference exists here, seems, in a 
certain sense, undeniable. But this difference evidently 
agrees, as Petersen" has stated, with the geographical 
separation, and Winther’s 0 observations go to show 
that this separation is sometimes evanescent. “The 
entire alteration in the Herring inhabiting the Sound”, 
he writes, “may be summed up as follows. The little 
Baltic Herring (Kivik Herring, Nilss.), which flocks 
together at the beginning of autumn at the south end 
of the Sound, advanced in 1867 right to the middle 
of the strait, north of the Flint Channel, where it found 
the great basin known as the “ Hulkene ’ untenanted by 
the Bottom Herring c , which had already departed. After 
the spawning it followed the northward current out 
of the Sound into the south of the Cattegat, whence 
it returned year after year to its old spawning-place, 
constantly increasing, under the favourable influence 
of more congenial environments (the greater saltness 
of the water?), in size and fecundity. It continued to 
“improve” in this manner until 1873, when its deve- 
lopment had advanced so far that it could no longer 
content itself within the confined limits of the Sound, 
but as it gradually attained the size and form of the 
“ Kulla Herring ”, began to repair to the spawning- 
places of the latter variety. Only few returned in 1875 
to the old spawning-places in the Sound, where a new 
stock of Baltic Herring this year (1875) replaced the 
old one in the Hulkene, north of the Flint Channel”. 
The Stromming can thus become Kulla Herring, an 
alteration which, as we have seen, involves nothing 
more than a higher degree of the typical development 
of the species. But it by no means follows that all 
Strommings become Herrings, nor does it seem possible 
for anyone to show that all young Bohuslan Herrings, 
loddsillar as they are called, in course of time become 
Ocean Herrings. 
That a particular stage of development under per- 
manent circumstances may become fixed as the termi- 
nation of the development of a species under those 
circumstances, is nothing unusual, and the characters 
of youth, especially in fishes that breed before they have 
attained their full specific size and development, may 
become hereditary and, under certain conditions, remain 
unaltered. This is, no doubt, the explanation both of 
the actual difference between the average Stromming and 
the average Herring, and of the fact that the young of 
the so-called Spring Herring and Coast Herring differ 
from the fry of the Autumn Herring and Ocean Her- 
ring''. But the difference appears, to the best of our 
knowledge, only in the averages and, probably, only 
° Kritilc etc., Vid. Meddel. Naturh. For. Kbhvn, 1888, p. 1. 
b Nord. Tidskr. Fisk., Aarg. 3 (1876), p. 12. 
c The name given by the fishermen to the shoals of larger Herring in the Sound. 
d “II faut necessairement admettre la residence de ces poissons sur des fonds differents, ou la diversite de la grandeur et de la gros- 
seur constitue autant de varietes on de races qui se perpetuent par voie de generation’ ; Cuv., Val., 1. c., XX, p. 49. 
