280 



and east, and the other 6| miles to the north and west. A male, caught in December 

 1911. 25 miles to the north and east, was " half ripe." 



Females. — The condition of the ovaries was recorded for only 5 of the 24 females. 

 One, captured in December 1911, 21 miles to the north and east, was " nearly ripe " ; 

 another, taken in January 1912, 17 miles to the north and east, was " spent," and 

 the third, recaptured in June 1912, off Auskerry, Orkneys, 59 miles to the north 

 and east, was described as " apparently spent." 



EXPERIMENT V. 



nth October \^n. 



In this experiment, 100 marked plaice were Uberated, 37 males, 60 females, and 

 3 whose sex was not determined. The males ranged in size from 24*5 to 40 cm., and 

 8 were under adult size ; the females measured from 26 to 56 cm., and 31 were under 

 adult size on liberation. 



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

 follows : — 



* One at 24 5 cm. 



The fish used in this experiment were taken by the " Goldseeker " on the 10th 

 October, in the Dornoch Firth, and marked before 4 p.m. They were hberated the 

 next day at 9 p.m. 



The number recaptured was 56, or 56 per cent., 24 males (64 '9 per cent.), 30 

 females (50 per cent.), and 2 of unknown sex (66*6 per cent.). On recapture, 23 of 

 the males were of adult size, ranging from 33*4 to 43*4 cm., and averaging 37*2 cm., 

 as compared with a range of from 31 to 40 cm., and a mean of 35"5 cm. on libera- 

 tion ; they were at liberty for from 15 to 594 days, the average being 237 days ; 

 they migrated distances of from 2^ to 89| miles, the mean being 23 "6 miles, and the 

 average rate "9 mile. Sixteen of the females were of adult size on recapture, 

 averaging 44*8 cm., and varying from 38*1 to 55*5 cm., as against a range of from 34 

 to 55'5 cm., and an average of 41 "1 cm. on liberation ; they were at hberty for from 

 32 to 521 days, the mean being 298 days ; they travelled distances of from 2| to 106 

 miles, the mean bieng 31*7 miles and the mean rate '97 mile. Fourteen of the 

 females were under adult size on recapture, ranging from 34 to 37*9 cm., and 

 averaging 36*2 cm., against an average of 36'1 cm., and a range of from 38*5 to 41 

 cm. on hberation ; they were at liberty for from 11 to 237 days, the mean being 97 

 days ; they moved from 3| to 82 miles, the average being 33*2 miles, and the mean 

 rate of movement 3*3 miles. 



The Extent and Direction op Migration. 



First Quarter. — In the remainder of October, 1 male and 2 females were re- 

 captured, the male and 1 of the females in " the Moray Firth," and landed respec- 

 tively at Ostend and Gee'steraiinde ; the other female was taken north-east of 

 Kinnaird Head, at 43| miles distant to the east and south. 



In November, 6 females and 1 of unknown sex were recaptured ; 1 female was 

 taken in the " Moray Firth," and landed at Ostend ; 3 were recovered on Smith 

 Bank, 1 at a distance of 3i miles to the south and east, and the other 2 at 8 miles 

 in the same direction ; the fish whose sex was not ascertained was also captured 

 on Smith Bank, at a distance of 8 miles to the south-east ; of the other 2 females. 



