23? 



" spawning " ; and another, taken in March 1912, off Noss Head, in the Moray 

 Firth, was "ripe." 



Among those " immature " was 1 , measuring 34"5 to 36"1 cm., taken in the Moray 

 Firth, off Dunbeath, 96 miles to the south and west, in February 1912. 



Females. — The condition of the ovaries was ascertained in 18 out of the 20 

 recaptured. 



None was " ripe," but 3 were " nearly ripe." Two were taken in November 

 1911 ; 1, 12 miles to the north and west, and the other north of Kinnaird Head, 82 

 miles to the south and west ; a third was taken in January 1914, after 1023 days, 

 20 miles to the south and west. 



Six were " spent." One recaptured in June 1911, east of the Orkneys, 33 miles 

 to the south and west ; 2 taken in July 1911, 11 and 12 miles to the north and west ; 

 and another in April 1912, near Buchanness, 118 miles to the south and west ; 

 the fifth in May 1912, also near Buchanness, at a distance of 104 miles to the south 

 and west ; and the last in June 1913, to the north of the Shetlands, off Balta, 84 

 miles to the north and east. 



EXPERIMENT VI. 



nth October 1911. 



This experiment was made on 12th October 1911, when 100 marked plaice, 

 comprising 32 males, 64 females, and 4 whose sexes were not determined, were 

 liberated about 35 miles east of Fair Isle, 59° 44' N. ; 0° 33' W. The males measured 

 from 28 to 51 cm., and 5 were under adult size on liberation ; the sizes of the females 

 varied from 27 "5 to 65 cm., and 25 were under adult size on liberation. 



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

 follows : — 



The fish used in this experiment were recaptured by the " Goldseeker " in 

 Burghead Bay, on the south shore of the Moray Firth, in the early afternoon of the 

 11th October, and they were Hberated on the 12th at 5.30 p.m., 2 having died 

 in the interval. 



The number recaptured was 42, or 42 per cent., viz. 14 males (43-7 per cent.), 

 26 females (40-6 per cent.), and 2 whose sexes were unknown. All the males were 

 of adult size on recapture, averaging 41-4 cm., and ranging from 34 to 50 cm., as 

 compared with an average of 40-3 cm., and a range of from 34 to 51 cm. on libera- 

 tion ; thev were free for from 15 to 882 days, the mean being 213 days ; they 

 travelled distances of from 18 to 397 miles," the average being 111-6 miles, and 

 the mean rate was 5-2 miles. T>^enty-one of the females were of adult size, ranging 

 from 39-3 to 58-2 cm., and averaging 46-1 cm., as against a range of from 35-5 to 

 55 cm., and an average of 43-6 cm., when liberated ; they were at hberty for from 

 16 to 586 days, the mean being 262 days ; they migrated from 23 to 170 miles, 

 the mean being 87-5 miles, and the mean rate was 3-3 miles. Five of the females 

 were under adult size on recapture, averaging 34-2 cm., as compared with 33-4 cm. 

 on liberation ; they were at hberty for an average period of 160 days, and migrated 

 distances of from 63 to 125 miles, the average being 94 miles, and the mean rate 

 5-9 miles. 



Extent and Direction of Migration. 



First Quarter.— A male and a female were captured in the remainder of October, 

 the male 18 miles to the north and west, and the female 40 miles to the southwards. 



