DEVELOPMENT AND LIFE-HISTORIES OF TELEOSTEAN FISHES. 817 
where they were thus put within reach of the gulls as well as the pollack themselves. 
On the 38rd August the shoals of young cod, 2 inches and upwards in length, presented 
the following external colouration :—Three or four parallel lines of square spots, reddish- 
brown and more or less bright, extended along the sides, which with the head showed 
an alternating silvery or golden gloss. Sars thinks that they are driven shorewards 
when 2 or 3 inches long, by wind and currents, and seek protection from the pollack 
among the Algz at the bottom. Moreover, it would appear that the shoals succeeded 
each other, since they went off as they grew older. In the beginning of October, 
having attained the length of 4 or 5 inches, they grow more rapidly, reaching in 
the middle of November the length of 6 inches, while on the 10th of December they 
measure 6 inches to 8 inches. Towards the end of winter they decrease in numbers. 
Sars states that the last fishes to appear amongst the Algz were no larger than the 
first, and that there must of necessity be a succession of shoals. Indeed, he describes 
two varieties, viz., the thickish, reddish-yellow kind, living chiefly amongst the Algz, 
and swallowing large numbers of reddish crustaceans, and a second kind of a light 
ereen or greyish shade frequenting sandy ground, where the Crustacea mentioned were 
rare—these thinner fishes living on Annelids and young Cott. Towards the end of 
February he followed them further out to sea, and found them measure on an average 
12 inches, and he was of opinion that the “ Alow-fish” were one year old. The 
greatest number of these “ Algv-fish” (1 foot long) are caught, it may be noted, in 
summer; but towards autumn their numbers are fewer. Accordingly, Sars concluded 
that the “going out” takes place in the second year, and that three years, or at most 
four years, hardly elapse before the fishes return to their native sites as full-grown 
cod, ready to reproduce their species. Considerably larger fishes than the forms found 
in February (1 foot long) he estimated at two years old, and in these the generative 
elements were found at Lofoten not to be fully developed, the smallest breeding fish 
being nearly 1 yard in length. On the other hand, he had seen young cod 1 foot in 
length in the fish-market of Christiania, which had mature roe and milt. 
Hitherto no very young gadoids have been captured in January, February, or March, 
and it is the end of April before such appear; indeed, they are more surely obtained in 
May in St Andrews Bay. Moreover, it does not follow that the smallest always occur in 
the earliest months, for some are found in May as small as any in April. The least of 
those hitherto secured was about 5 mm., several having been captured on the 30th April, 
and others of the same size on the 19th of May and Ist June. Now the little cod reared 
in the laboratory to a certain stage are about three-fourths the length of this on the 9th 
May, and though we cannot antedate the spawning period of the cod from personal 
observation sooner than March, there is no reason to doubt the occurrence of an earlier 
issue of ova and spermatozoa in some cases; indeed, the general variability would hold. 
This, and the differences in the rate of growth known to occur even in those spawned 
at the same moment, give us the somewhat wide range in size with which we are familiar 
in the group. 
VOL. XXXV. PART III. (NO. 19), 6 M 
