of the Fishery Board for Scotland. 



209 



The third or smallest group represented has its upper limit, as stated, 

 about 24cm. (9| inches), but the lower limit cannot be determined from 

 these collections, the smallest specimens measuring only 21cm. (216mm.), 

 or 8| inches, but it may be inferred from the consideration of the brill in 

 the other collections. 



The principal reason of the unequal representation of the three groups 

 above referred to in the collections from the Moray Firth is no doubt the 

 depth of water in which the trawling was carried on, 4| or 5 to 13 and 

 more fathoms. The smaller brill frequent the shallower water, and thus 

 the proportion taken of the larger members of the second series is greater 

 than the proportion of the smaller members, while comparatively few of 

 the third or smallest series were caught, aud they were only the larger 

 fishes of that series. 



It appears to me that the size — or age-groups — of the brill in these 

 collections may be represented as follows with approximate accuracy : — 





Inches. 



Centimetres. 



1 



1 year old. . . " 



2 „ „ . . 



!::::':: 

 i 5 ;: ;; . . 



! 6 „ „ 

 7 „ 



2f-41 

 Ul 

 3-10 

 10-12 

 12-14 

 14-16 

 16-17* 



7 0-11-5 

 12-17-5, 18 

 19, 20-24 

 25-30 

 30-35 

 35-40 

 40-44 



At the same time, it must be recollected that the sexes were not distin- 

 guished and separately measured, and, judging from the case in other 

 flat-fishes, the growth of the males will be slower than that of the females 

 after the size of maturity is reached, and it is thus possible that what 

 appears to be an age-group after that size may only be a sex-group. But, 

 from the remarkable agreement in the various collections, as shown by the 

 aggregate or combined curves, and by the separate curves, as to the 

 existence of a division between groups at 34cm. to 35cm., it is clear to me 

 that this confusion does not exist below that point, but that the sexes so 

 far grow equally; and, therefore, that sexual maturity is not reached 

 either by males or females till a size above 34cm. to 35cm. (13| to 13| 

 inches), and that the great spawning group lies, in winter, between 35cm. 

 and 41cm. or 42cm. (14 to 16, 17 inches), when they appear to be about 

 six years old. 



It may be added that the weight of a brill at a given length is much 

 greater than with other flat-fishes, except the turbot.* The weight of a 

 plaice about 39cm. is approximately 650 grammes ; that of a brill about 

 the same size is approximately 950 grammes. Thus the amount of growth 

 of the brill by the increase of, say, 1cm. in its length is much more than 

 in the plaice with a similar increase. 



COD (Gadus collar i as). 



The number of cod measured and dealt with in the present paper, 

 and belonging to 50 separate collections, is 3813, which, with those 

 treated of in the paper published previously, makes a total of this species 

 of 7176, most of which belong to the two or three first generations. 



The main points brought out in the paper referred to were that the 

 young cod of the year were on an average in October, when about six or 



* See Tables in Twenty-second A nnual Report, op. 144, 219, 

 O 



