962 
SCANDINAVIAN FISHES. 
which show the most marked alterations of growth — 7, 
8, 10, and 13 in the table — the oldest Fat Herrings 
from Stavanger (Column 6), though smaller on an aver- 
age than the Baltic Herrings (Column 2), have advanced 
further than the latter. Their development has pro- 
ceeded more rapidly. Similarly the youngest Scotch 
Herrings (Column 7), though inferior in average size 
Averages in Herrings from 
Bohuslan. 
Scotland. 
Bohuslan. 
Scotland. 
Number of specimens measured 
11 
5 
8 
5 
Length of the body expressed in millimetres 
221 
221 
263.4 
260 
Length of the head in % of the length of the body 
20.5 ’ 
20.3 
20.3 
20. a 
Preabdominal length „ „ „ ,, „ „ „ „ 
32.7 
33.4 
33.i 
33.8 
Distance between the anal fin and the tip of the snout „ ,, ,, „ „ „ „ „ 
72.8 
73.7 
74.3 
75.2 
to the Herrings from Bohuslan (Column 3), have out- 
stripped the latter in the alterations of growth. The 
more oceanic its home, the more rapid and more vi- 
gorous is the development of the Herring type. This 
is still more clearly shown by comparing with the last 
two columns Bohuslan Herrings more nearly approach- 
ing to them in a.o;e: 
The same results may be deduced from Lundberg’s Ocean Herrings with the organs of generation equally, 
tables by thence selecting for comparison Baltic and or at all events not too unequally developed: 
Averages in Herrings from 
The Baltic. 
Bohuslan. 
Number of specimens measured 
11 
42 
19 
6 
7 
Length of the body to the end of the caudal lobes, expressed in mm 
186.1 
205. g 
223.3 
294.2 
247.9 
,, „ ,, head in % of the above length of the body 
21.4 
20.9 
20.8 
20.3 
18.6 
Number of specimens measured 
11 
13 
6 
7 
Length of the body to the end of the caudal lobes, expressed in mm 
186.i 
201.8 
294.2 
247.9 
Vertical diameter of the eyes in % of the above length of the body 
5.5 
5.2 

4.7 
4.5 
The Baltic form (the Stromming) thus fails, even 
at its most advanced age, to attain averages equal to 
those shown by the much smaller Herrings from Bo- 
huslan in the last column. The Strommings, as Nils- 
son has pointed out, have on an average a larger head 
and larger eyes; but this is only a general rule, for 
exceptions are not uncommon. 
Between the Stromming and the Herring, however, 
the averages obtainable from Lundberg’s tables show 
another distinction, the significance of which is all the 
greater, since it indicates a different direction of deve- 
lopment or at least a divergent tendency, and seems 
most naturally to admit of explanation, as we have 
above stated of the analogous relations in the Salmon- 
oids, on the assumption either that the forms are still 
in process of differentiation from each other, or that 
one of them is undergoing a degeneration expressed by 
reversions to the earlier stages of development. A rule 
of general validity, which I stated in 1882" in a de- 
scription of an hermaphroditic example of this species, 
tells us that, after the dorsal fin has passed through the 
forward removal which, as Sundevall'" first showed, 
attends the development of the Herring from the larval 
stage, there ensues, during the subsequent growth, a 
backward removal of this fin. In a preceding table 
(p. 961) we have also seen that the percentages for 
the distance between the dorsal fin and the tip of the 
snout (relation no. 5) increase with age. The ventral 
fins share in this backward motion (relation no. 8). 
Let us now examine these relations in the Stromming, 
according to Lundberg’s tables. For this purpose we 
divide the specimens measured by him into four groups, 
a Arch. Biol., vol. Ill, p. 269. It should, however, be remarked that I was prevented from reading the proofs of this paper, which 
was printed at Brussels, and that a number of misprints, especially in the numerals, have consequently been overlooked. 
6 Om fislcyngels utveclcling, Vet.-Akad. Handl. 1855, p. 20. 
