182 



One female, of 38-5-48-1 cm., taken in December 1912, after 928 days, at a 

 distance of 13 miles to the north and east, was described as " nearly spawning." 



None was described as " ripe," but 3 were " nearly ripe." One of these, which 

 measured 36-5-39-4 cm., was taken off Banff in February 1911 ; another, of 32-42-3 

 cm., in February 1912, off Auskerry, Copinshay, Orkney Isles, at a distance of 126 

 miles ; the third, which measured 32-45-9 cm., was captured in September 1912, 

 24 miles to the south and west. 



Four were " spent," 1 caught in July 1911, 35 miles to the north-west, 1 in May . 

 1912, the position of capture not being ascertained ; a third, also in May 1912, 

 8 miles to the south and east, and the fourth in May 1914, after 1447 days, l8 miles 

 to the north and west. 



Two taken in March 1911 were described as "spent or immature"; they 

 measured 32-5-38-4 cm. and 34-5-38-3 cm., and were caught 34 and 32 miles to the 

 north and west. 



Among those of adult size, whose ovaries were said to be "immature," were 

 3 taken in April, and measuring 36-39-8 cm., 36-5-38-9 cm., and 29-40-9 cm. ; 

 they were caught 26 miles to the south and west, 8 miles to the south and east 

 and 46 miles to the south and west respectively ; another, of 28-38-2 cm., was 

 taken in the Firth of Forth, between Largo and Elie, at a distance of 75 miles, in 

 February 1912. 



EXPERIMENT II. 



21s/, October 1910. 



In this experiment, 282 plaice were marked and liberated, comprising 114 males, 

 152 females, and 16 whose sexes were not ascertained. The sizes of the males 

 ranged from 27 to 41 cm., and 14 were under the adult size on liberation ; the 

 females ranged from 27 to 45-5 cm. in length, and 90 of them were below the adult 

 size. Those whose sexes were not recorded varied in length from 33-5 to 40 cm. 



The numbers marked and recaptured, arranged in 5-cm. groups, are given in 

 the following table : — 



cm. cm. cm. cm. 



2.5-30-5 31-35o 36-40-.'5 41-45-5 Total. 



F. Lib. ... 6 46 83 17 152 



F. Recap. . . 2 27 69 14 112 



M. Lib. . . 3 51 59 1 114 



M. Recap. . . 1 33 42 — 76 



?Lib. ... — 5 11 — 16 



? Recap. . . — 1 6 — 7 



The fish used in this experiment were trawled by the " Goldseeker " early in 

 the afternoon of the 19th October, in Aberdeen Bay, between Slains Castle and 

 ColUeston. As there was a heavy sea that day, the vessel anchored in Peterhead 

 Bay, where it had to remain until the morning of the 21st, when it steamed to 

 Aberdeep Bank and hberated the fish about noon. 



The number recaptured was 195, or 69-1 per cent., namely, 76 males (66*6 per 

 cent.), 112 females (73-7 per cent.), and 7 of unknown sex (43-7 per cent.). 



Of the males, 71 were of adult size on recapture, averaging 38-1 cm., and ranging 

 from 33 to 49-2 cm., as compared with an average of 36-1 cm., and a range of 

 from 32 to 40-5 cm. on liberation ; they were at libeity for from 4 to 1326 days, 

 the mean being 244 days ; they migrated distances of from 4 to 194 miles, the 

 mean being 63-4 miles, and the mean rate of movement 2-6 miles. Five of the 

 males were under adult size, the average being 31 cm., as compared with a mean 

 of 31-5 cm. on hberation ; they were free for an average period of 156 days, and 

 migrated a mean distance of 55-4 miles, at an average rate of 3-5 miles per 10 days. 



Seventy-nine of the females were of adult size on recapture, the mean being 

 41-9 cm., and the range from 38 to 51-9 cm., as compared with an average of 38-8 

 cm., and a range of from 33 to 44-5 cm. on liberation ; their periods of freedom 

 varied from 5 to 799 days, and averaged 283 days ; they moved distances of from 



