294 



distance of 15'9 miles at the mean rate of "3 mile. Three were below the adult size, 

 averaging 32-5 cm., and were free for a mean period of 191-6 days. 



The Extent and Direction of Migration. 



First Quarter. — Only 1 fish, a male, was taken in this quarter, viz. in May, 16| 

 miles to the south and west, near Portmahomack. 



Second Quarter. — In September, a female was got at an unspecified place in the 

 Moray Firth, and in October, a male off Burghead, 15| miles to the south and west. 



Third Quarter. — Two females were found in November, 1 at an unspecified place 

 in the Moray Firth, and the other in the Dornoch Firth, 23 miles to the westwards. 

 A male was taken in December, at Smith Bank, 18 miles to the north and east, 

 and another male in January 1912, recorded as caught in the "Moray Firth." 

 Only 4, therefore, were recaptured in this quarter. 



Fourth Quarter. — Three males and 2 females were recajotured in February 

 1912, 2 of the males and the 2 females to the north and west, at distances of from 12 

 to 19 miles, a female and 1 of the males in the Dornoch Firth, close inshore, and 1 

 of the males south-west of Berriedale Ness ; the remaining male had taken a long 

 journey, and was recaptured 16 miles W.S.W. of Cape Wrath, at a distance of 13H 

 miles. Three males were taken in March, all to the northwards. 1 at a distance 

 of 9 miles, off Berriedale Ness, 1 off Strathie Point, Orkneys, at 85 miles, and the 

 third on the north-west coast, 8 miles N.W. of Loch Inchard, at a distance of 128 

 miles. A male was recovered in April, 11| miles to the north and west, at the 

 mouth of the Dornoch Firth. 



In the 12 months following liberation, 16 of the marked plaice, or 76-2 per cent., 

 were taken, positions being known for 13, or 6r9^ per cent. ; 5 had moved to the 

 north and east, 5 to the north and west, 2 to the south and west, and 1 to the west. 



A female was recaptured in July 1912, 13 miles to the north and west, off Berrie- 

 dale Ness. In February 1913, 3 females were taken, the position of capture of 1 

 being unknown ; the other 2 were found to the north and west, in the Dornoch 

 Firth, at 15| and 17 miles. The last fish to be taken was a male caught in March 

 1914, after 1073 days, only 7^ miles distant, to the south and west. 



Distances travelled — 10 miles and under. — Two, both males, were taken under 

 10 miles, 1 to the north and east, and the other to the south and west. 



10 to 20 miles. — Eleven, or 64*7 per cent., were taken at distances of from 12 

 to 19 miles, 6 males (54-5 per cent.), vath an average of 14"7 miles, and 5 females 

 (83"3 percent.), with a mean of 15-9 miles ; 3 of the males and all the females were 

 found to the north and west, 1 male to the north and east, and 2 to the south and 

 west. 



20 to 50 miles. — Only 1, a female, was recaptured within these limits, 23 miles 

 to the westwards. 



50 to 100 miles. — A male was taken 85 miles to the north and east. 



Over 100 miles. — Two males were recaptured on the west coast, 1 north and east 

 of Cape Wrath, at a distance of 131 miles, and the other off Loch Inchard, at a 

 distance of 128 miles. 



Maturity. 



Males. — The condition of the testes was recorded for 3 of the 12 recaptured. 

 One, caught in March 1914, after 1073 days, 7| miles to the south and west, was 

 " spawning," and another, taken in March 1912, off Strathie Point, north coast, 

 at a distance of 85 miles to the north and east, was " ripe." 



Females. — The condition of the ovaries was ascertained in 6 of the 9 recaptured. 

 One was " spawning " ; it was taken in February 1913, 15| miles to the north and 

 west, in the Dornoch Firth ; another, found in February 1912, 15 miles to the north 

 and west, in the Dornoch Firth, was " nearly ripe," and the third, recaptured in 

 February 1912, in the Dornoch Firth, at a distance of 19 miles to the north and west, 

 was " spent." 



experiment III. 



I5th September 1911. 



In this experiment, 125 plaice were marked and liberated on the 15th September 

 1911, 60 males and 65 females. The males ranged in size from 25 to 48 cm., and 



