127 



and east. Thus, 46 of the 57 recapluied fish, whose positions were known, i.e. 

 80-7 per cent., were found within 20 miles of the station, viz. 19 males (73-1 per 

 cent.) and 27 females (87-1 per cent.). 



20 to 50 miles. — Six, or 10-5 per cent., of the fish were got between 20 and 

 50 miles of the station, 3 (11-5 per cent.) being males, with an average distance of 

 39'3 miles, and 3 being females, with an average distance of 25-5 miles. Four fish, 

 2 males and 2 females, went to the north and east, and 2, a male and a female, to 

 the north and west. 



50 to 100 miles. — Four of the marked plaice, or 7 per cent., went distances of 

 from 50 to 100 miles, 3 (11-5 per cent.) being males, going an average distance of 

 59-3 miles, and 1 female for a distance of 91 miles. All had gone to the north-east. 



Oi^er 100 miles. — Only 1 fish, a male, went a journey of over 100 miles. It was 

 recaptured off Flamborough Head, 219 miles off in a south-easterly direction from 

 the place of liberation. 



Maturity. 



Males. — Of the males recaptured, 23 were of adult size, and the condition of 

 the testes in 20 of them was ascertained. Two were " spawning," viz. 1, of 37-41*1 

 cm., taken off Aberdeen, at a distance of 46 miles, on 16th February 1913, after 

 282 days, and another, of 37-5-39-3 cm., caught on 25th April 1913, after 350 days, 

 15 miles to the north-west, off St. Andrews Bay. 



One was described as " ripe " ; it was caught on 18th March 1913, after 312 daj^s, 

 off Aberdeen, at a distance of 49 miles, and near the place where the spawning 

 male above referred to was captured. 



Three males were described as " spent " ; 1 was got in May 1912, 9 miles north 

 and west ; another was taken in August 1913, 5^ miles north and west, and the 

 third in September 1912, 13 miles to the south and west. 



A male, taken on 17th December 1912, 54 miles distant, close inshore off Aber- 

 deen, was " fully half-ripe." 



The other 13 adult males were " immature." One was caught in February 

 1913, after 280 days, in the Firth of Forth, off Pittenweem ; it measured 29-5-33-2 

 cm. Another, measuring 30-35-6 cm., was caught on 20th March 1914, after 

 679 days, only 2 miles to the north-west of the station. Of the remainder, 1 was 

 taken in May, 3 in June, 4 in July, 1 in August, and 2 in October. Most of them 

 were got near the station, at distances of from 4 to 18 miles, 1 to the east, 1 to the 

 west, 3 to the north-west, 3 to the north-east, 3 to the south-west, and 1 to the 

 south-east. 



Females. — Of the females, 17 were of adult size, the condition of the ovaries 

 being ascertained in 15. None was " spawning " or " ripe," but 4 were " spent." 

 One, of 44-43-7 cm., was taken in May, after 6 days, 5 miles to the south and 

 east ; another, of 50-5-49-8 cm., was caught on the day after liberation 11 miles 

 to the south-west ; the third, measuring 44-44 cm., was taken in May, after 17 

 days, also 5 miles to the south and west ; and the fourth, of 34-41*2 cm., was taken 

 in June 1913, after 400 days, 10 miles to the north and east. 



Two were " maturing," caught respectively in July and October, 4 and 5 miles 

 to the south and west. 



The other nine were " immature," and were caught as follows : — One in January 

 1913, after 255 days, 5 miles to the south and west ; it measured 34-38-8 cm. ; 

 1, whose size on liberation was about 40 cm., the size on recapture not recorded, 

 was caught in February 1913, after 292 days, off Aberdeen, 91 miles to the north 

 and east ; a third, measuring 39-42-2 cm., was caught in March 1913, after 305 

 days, 5 miles to the south and west. Of the remaining fish, 3 were taken in July, 

 2 at 12 miles, and 1 at 22| miles distant, 1 in August at 14 miles, and 2 in September 

 at 4 and 5 miles respectively. 



EXPERIMENT IX. 



^th December 1912. 



In this experiment 202 plaice were marked and liberated, 78 being males, 122 

 females, and 2 whose sexes were not ascertained. Tlie sizes of the males ranged 

 from 26-5 to 45 cm., and of the females from 27*5 to 54-5 cm. 



