51 



cent.) mtii an average of 8"3 miles, aiul 12 of them were found within the Firth of 

 Forth. 



20 to 50 miles. — Nine, or 32" 1 per cent., were recaptured between 20 and 50 

 miles, 3 males (17"6 per cent.), with an average distance of 30'8 miles, and 6 females 

 (54'5 per cent.) with an average of 30*7 miles. Two of the males and 4 of the 

 females were found to the north and east, and 1 of the males and 2 of the females 

 to the south and east. 



50 to 100 miles. — Only 1 fish was got between these limits, a male, which went 

 to the north and east, a distance of 50| miles. 



Over 100 miles. — Four fish (14:'3 per cent.), all males (23"5 per cent.), were 

 recaptured at distances of from 137| to 168 miles, the average being 156 miles. They 

 all migrated to the northwards, 3 being taken in the Moray Firth, and 1 just out- 

 side the hmit, east of Noss Head. 



The following table shows the numbers and percentages of those which were 

 caught in the Firth of Forth, and outside the Firth : — 



Males. — The condition of the testes was determined in 11 of the 19 males 

 recaptured. Three were "spawning," and all were recaptured in the Moray Firth, 

 1 measuring 29"5-37'2 cm., in March 1913, after 714 days, at a distance of 164 miles, 

 the mean rate of movement per 10 days being 2'3 miles ; another, measuring 

 28*5-36 cm., in April 1913, after 742 days, at a distance of 137^ miles, the mean 

 rate being 1*8 miles per 10 days ; and the third, of 31'5-39'2 cm., in March 1914, 

 after 1082 days, at a distance of 168 miles, the mean rate being 1*5 miles per 10 

 days. 



One male was " ripe " ; it measured 30"5-35"4 cm., and was caught in March 

 1912, after 348 days, at a position unknown. 



Three are described as "nearly ripe," 1, of 35-38*9 cm., taken in December 

 1911, 22| miles to the north and east ; another, of 32-35"6 cm., taken in October 



1911, 50i miles to the north and east ; the third, measuring 31-35*9 cm., also 

 taken in October 1911, 43| miles to the north and east. 



Females. — No female was "spawning," but 1, of 37-40*9 cm., captured in 

 February 1912, after 332 days. 24| miles to the north and east, eastwards of the 

 Forth, was " ripe." 



None was described as " nearly ripe," or " spent." 



Four females, of adult size on recapture, were said to be " immature " ; 1 was 

 got in the month of June, and another in September ; the third, taken in February 



1912, was " rather immature " ; it measured 36-41 cm., and was caught in the 

 Firth of Forth ; the fourth, taken in May 1912, west of St. Abb's Head, measured 

 32*5-39*5 cm. 



None of the fish recaptured in the Forth showed signs of maturity, and all the 

 recaptured fish which were under the adult size on recapture (5 males and 5 females) 

 were taken in the Firth of Forth. A male, recaptured in the Firth in March, and 

 thus in the spawning season, was " immature," though it measured 36*9 cm. ; 

 and a female, taken in February, in the Firth, in the spawning season, was also 

 " immature," though it measured 41 cm. 



EXPERIMENT IV. 



'2Uh Afrilim. 



In this experiment, 52 fish were marked and liberated, viz., 16 males, 35 females, 

 and 1 whose sex was not determined. The sizes of the males ranged from 29 cm. 

 to 39 cm., and of the females from 29*5 to 55 cm. Nine of the males and 17 females 



