204 



Maturity. 



Males. — The condition of the testes was recorded for 10 of the 11 males. 

 Two were "spawning," 1 , measuring 36-5-36-8 cm., caught in February 1913, 10 miles 

 to the north and west, and the other, of 36-5-39-9 cm. in February 1914, 30| miles 

 to the north and west. 



A male, of 36-36-3 cm., taken in January 1913, 35^ miles to the north and west, 

 was described as " ripe." One, of 35-5-34-8 cm., taken in December 1912, 24 miles 

 to the south and Avest, was said to be " nearly ripe." 



Two, described as " immature," were caught in the spawning season, both in 

 April, 1, 15 miles to the south and west, and the other 12 miles to the north and 

 west ; they measured respectively 34-5-35'7 cm. and 36-5-36-5 cm. 



Females. — The condition of the ovaries was ascertained in 23 of the 29 recap- 

 tured. Two were "spawning," 1, of 44-44-3 cm., being captured in February 

 1913, 15J miles to the north and west, and the other, of 42-5-43-4 cm., in March 

 1913, 8 rniles to the north and west. 



One was described as " nearly spawning " ; it measured 42-42 cm., and was 

 captured in DccemDer 1912, 10| miles to the westwards. 



Pive wei? aescribed as "spent," but the position of 1 was not recorded; the 

 others were taken as follows :— One in May 1913, 48 miles to the north and west, 

 off Rattray Head ; another, in March 1914. 9 miles to the north and west ; the 

 third, in Mav 1914, 9| miles to the north and west ; and the fourth, in February 

 1915, after 882 days, 7" miles to the north and west. 



Four were " nearly ripi " ; 1 was taken in November 1912, 42 miles to the north 

 and cast ; another, in December 1912, 17 miles to the north and west ; the 

 third, in November 1913, 56 miles to the north and sliglitly to the east ; and the 

 fourth, in January 1914. 8 miles to the north and west. 



Among those in which the ovaries were " immature," 1, of 39-39-5 cm., was 

 captured in April 1913, lOh miles to the west. 



EXPERIMENT VI. 



27th March 1913. 



One hundred plaice were marked in this experiment, 28 males and 72 females. 

 The males ranged in size from 29-5-41-5 cm., and 6 were under adult size, and the 

 females from 31-5 to 55 cm., of which 49 were under adult size. 



The numbers liberated and recaptured, arranged in 5-cm. groups, are as 



follows : — 



cm. cm. cm. cm. cm. cm. 



25-30-5 31-35-5 36-40-5 41-45-5 46-50-5 51-55-5 Total. 



F. Lib. . . — 34 31 4 2 1 72 



F. Recap. . . — 26 23 4 1 1 . 55 



M. Lib. . . 1 19 7 1 - — 28 



M. Recap. . . 1 14 6 1 — — 22 



The fish used were taken by the " Goldseeker " in the Firth of Forth, place un- 

 specified, on the afternoon of the 26th, and were liberated about 2 a.m. on the 27th, 

 after being in the tanks for 11 hours, " all in good condition." 



The number recaptured was 77, or 77 per cent., viz. 22 males (78-6 per cent.) 

 and 55 females (76-4 per cent.). All the males were of adult size on recapture, 

 ranging from 33-2 to 43-8 cm., and averaging 38-6 cm., as compared with a range of 

 from 29-5 to 41-5 cm., and an average of 34-8 cm. on hberation ; they were free for 

 from 5 to 671 days, the mean being 253 days, and they migrated distances of from 

 4 to 154 miles, the average being 36-6 miles, and the mean rate of movement 1-4 

 miles. Thirty-two of the females were of adult size, ranging from 38 to 55-3 cm., 

 and averaging 43-8 cm., as compared with a range of from 32 to 55 cm., and an 

 average of 38-8 cm. on hberation ; they were at hberty for from 4 to 1457 days, the 

 mean being 294 days, and they moved distances of from 3 to 198 miles ; the mean 

 being 30-5 miles, and the average rate 1 mile. Twenty-two of the females were 

 under the adult size on recapture, ranging from 31*3 to 37*9 cm., and averaging 

 35-3 cm., as compared with a range of from 31*5 to 37*5 cm., and a mean of 34*2 



