145 



females went to the north and east, being recovered off the coast of Aberdeenshire ; 

 a female was recaptured at a distance of 56 miles to the south and east, off the coast 

 of Northumberland ; a male was taken in the Firth of Forth, off Newhaven, at a 

 distance of 63 miles. 



Over 100 miles — One fish onl3% a male, went a journey of over 100 miles, being 

 recaptured off Spurn Point, a distance of 187 miles to the south and east. 



Maturity. 



The condition of the testes was ascertained in 17 of the recaptured males. 



Two were "spawning"; 1, measuring 39-5-4r7 cm., was taken in March 

 1913, after 599 days, between Aberdeen and Stonehaven, at a distance of 45 miles 

 to the north and west ; the other (" partly spent ") measured 30-5-34-5 cm., and 

 was also caught in March 1913, after 616 days, at Aberdeen Bank, a distance of 36 

 miles to the north and east. 



One male, of 37-37-1 cm., recaptured in December 1911, after 147 days, was 

 " nearly ripe," but the position where it was taken was not recorded. Another 

 male, of 46'5-45-8 em., caught in September 1911, after 57 days, 12 miles south 

 and west, was " about half-ripe." 



AU the others were " immature " ; none of those of adult size was caught 

 within the spawning season. 



Females. —T\i.e condition of the ovaries was recorded in 16 of the 19 recaptured. 



None was " spawning " or " ripe " ; 1, of 34-43-6 cm., taken in July 1913, 

 after 728 days, far off the coast of Aberdeen, at a distance of 61 miles, was " spent " ; 

 another, of 29-38*5 cm., caught in July 1912, after 366 days, near Tod Head, at a 

 distance of 34 miles, was " apparently spent." 



All the others were " immature," including 1, of 35-40*6 cm., caught in March 

 1913, after 614 days, at Aberdeen Bank, 38 miles distant. 



EXPERIMENT II. 



\2ih Sepemher \^\\. 



In this experiment, 102 plaice were marked and hberated, comprising 30 males, 

 69 females, and 3 of unknown sex. The sizes of the males ranged from 325 to 42 

 cm., and of the females from 28 to 64 cm. Only 2 males were under the adult 

 size (33 cm.) and 21 of the females (38 cm.). The numbers liberated and recaptured 

 are shown in the accompanying table, in groups of 5 cm. 



The fish which were marked were taken at Station VI., Firth of Forth (off St. 

 Mo nans), between 6 and 8 p.m. on the 11th Sepi ember, and were set free at 1 .40 a.m. 

 on the 12th. 



The number recaptured was 61, or 59-8 per cent., namely, 14 males, or 46-6 per 

 cent., 46 females, or 66-6 per cent., and 1 of undistinguished sex. 



Of the 14 males, the periods of freedom varied from 6 to 555 days, the average 

 being 179 days ; the sizes on liberation ranged from 33-5-41 cm., the average 

 being 36-5 cm. ; the sizes on recapture varied from 34-8 to 40-8 cm., the mean 

 being 37-8 cm. ; the distances migrated were from 2 to 208-5 miles, the average 

 being 49-9 miles, and the mean rat^ of travel 2-78 miles per 10 days. 



Forty of the females were of adult size on rccaptuie, viz. from 38-1 to 54*1 

 cm., the average being 42*6 cm., compared with a range of from 35-5 to 54 cm., on 

 liberation, and an average of 40"3 cm. ; they were free for from 3 to 897 days, the 



