168 



50 to 100 miles. — Eight of the marked plaice, or 11-6 per cent., were recaptured 

 at distances of from 55| to 84 miles, namely, 4 males (12-5 per cent.), with an 

 average of 73 miles, and 4 females (10'8 per cent.), with an average of 58"5 miles. 

 Two of the males and 1 of the females went north and east, 1 of the males and 3 

 females north and west, the remaining male being found to the south and east. 



Over 100 miles. — Nine fish, or 13 per cent., were taken at distances of from 103 

 to 247 miles, namely, 7 males (21-9 per cent.), with an average distance of 157-5 

 miles, and 2 females (5-4 per cent.), with an average of 117 miles. Five of the males 

 went to the north and east, 1 of the males to the south and east, the remaining male 

 and 1 of the females to the south and west, and 1 of the females to the north and 

 west. Two of the males and 1 of the females were got off the English coast, and the 

 remainder in the Moray Firth, and the north coast of Scotland. 



It may be noted that four of the plaice had returned to the Firth of Forth. 



Maturity. 



Males. — The condition of the testes in 24 of the 32 males recaptured was ascer- 

 tained. 



Four were " spawning," and were taken as follows : — One, of 37'5-37'6 cm., 

 on the 15th December 1912, at Aberdeen Bank, at a distance of 38 miles to the north ; 

 another, of 35-5-38'l cm., in February 1913, in the same locality, at a distance of 37 

 miles ; the third, also in February 1913, at a distance of 35 miles, near the same 

 place ; the fourth, in February 1914, in Edrachilles Bay, on the west coast of Scot- 

 land, at a distance of 236 miles. 



Three were described as " ripe," 1 taken in the Moray Firth, off Whitehills, in 

 February 1913, at a distance of 110 miles ; another, in the same month, at Aberdeen 

 Bank, at a distance of 37 miles ; and the third, in February 1914, off Wliitby, 

 at a distance of 104 miles, to the south and west. One, said to be " three-quarters 

 ripe," and measuring 36-5-38"2 cm., was captured in December 1912, 6^ miles to 

 the south and west. 



Two were " spent," both got in May 1913, one, 15J miles to the south and west, 

 and the other, at Rona, north-west of Cape Wrath, at a distance of 247 miles. 



Of 10 males of adult size whose testes were " immature," 1 was recaptured within 

 the limits of the spawning season. It measured 30-33'2 cm., and was taken in 

 April 1913, in the Firth of Forth, off Pittenweem, at a distance of 56 miles. 



Females. — Of the 39 fish recaptured, the condition of the ovaries was ascertained 

 in 34. Three were " spawning," 1, of 41-41"9 cm., got in February 1913, at Aber- 

 deen Bank ; another, of 47-5-49-5 cm., in March 1914, near the Bell Rock, at a 

 distance of 36 miles to the north and west ; the third was caught in March 1915, off 

 Hartlepool, at a distance of 103 miles to the south and west. 



Four females were described as "spent." Two were taken in April 1914; 1, 

 measuring 38-5-45-8 cm., to the east of St. Abb's Head, at a distance of 22 miles to 

 the south and west ; the other, which measured 37-5-50"6 cm., at Aberdeen Bank, 

 at a distance of 38 miles to the north and east ; 1, caught in April 1915, after 1011 

 days, was taken near the coast north of the Bell Rock, at a distance of 38 miles to 

 the north and west ; the fourth, which measured 34'5-45-7 cm., w^as found in the 

 same locality, at a distance of 33 miles. 



Of 9 adult females whose ovaries were " immature " on recapture, 1 was taken 

 in the spawning season ; it measured 38-5-39-2 cm., and was recaptured off Buck- 

 haven, in the Firth of Forth, at a distance of 65 miles. 



EXPERIMENT II. 



215/ September 1912. 



In this experiment, 100 plaice were marked and hberated, 37 being males, 61 

 females and 2 of undetermined sex. The males ranged in size from 31 cm. to 

 44"5 cm., and the females from 33 cm. to 56-5 cm. ; 7 of the males and 30 of the 

 females were under the adult size on liberation. The numbers liberated and 

 recaptured, arranged in 5-cm. groups, were as follows : — 



