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 3rd 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 Algae 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 Algae 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 Algae, 

 and swallowing large numbers of reddish crustaceans, and a second kind of a light 

 green or greyish shade frequenting sandy ground, where the Crustacea mentioned were 

 rare — these thinner fishes living on Annelids and young Cotti. 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 " Algae-fish " were one year old. The 

 greatest number of these "Algae-fish" (l 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 (l 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 1st 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 



