of the Fishery Board for Scotland. 



77 



for the males ; the averages in the two months being for females 62*9 and 

 90-1 mm., and for males 60*6 and 86-9. After August the growth does 

 not appear to be rapid, the mean-size of the females of the group in October 

 being on the 26th — for 100 specimens from 79 mm. to 108 mm. — 95'3 

 mm., and on 31st (for eighty-six specimens from 80 to 111 mm.) 95*4 

 mm. ; for the males the October averages are 89*2 mm, and 88"0 mm. In 

 winter, as might be expected from the habitat in this case, growth is 

 slow, as may be seen by comparing the corresponding groups in October- 

 December and Maich, April. 



In one or two instances two annual groups in the same series of 

 measurements appear fairly complete, thus affording opportunity to 

 deduce the amount of annual growth. Among the females on October 

 31st the first series has a mean-size of 63*3 mm. (or about 2| inches), the 

 range extending from 57 to 70 mm. ; the second series, as stated, is 95-4 

 mm., thus showing an annual increment of 32' 1 mm. Among the males 

 the first series also ranges from 57 to 70 mm,, and has an average size of 

 62'4 mm. ; the second series, from 73 to 98 mm., has a m'ean-size of 88*0 

 mm., showing an annual increment of 25*6 mm. In the December 

 series, the average size of the males in the first group is 62*8 mm. and 

 in the second group 87*6 mm., showing an annual increment of 24*8 

 mm. Among the females the first group has an average of 62*3 mm., 

 and the second group an average of 94*2 mm. ; the annual increment 

 indicated being 31 "9 mm. 



Looking to these facts and the absence of the smaller forms in June, 

 August, and the early part of September, the occurrence of one or 

 two at the end of September, and the increase in their numbers later, 

 I think there is little doubt that the first series represented in March is 

 about one year old. And the phenomena presented by the ovarian eggs 

 at different periods, and the measurements of the mature and immature 

 fishes, as set forth above, make it probable that sexual maturity is not 

 reached by the group until the second year. The largest specimen 

 obtained, it may be added, the sex of which was not, however, 

 ascertained, measured 156 mm. or 61 inches; it was from the Forth. 

 The largest female determined was 136 mm. or 5f inches, and the largest 

 male 141 mm. or 5^^^^ inches. They were both from the Solway. 

 Contrary to what obtains among flat-fishes the males reach a size quite 

 as large as the females, and presumably attain the same age. 



[Tables. 



