244 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
Wales at once emigrate to the South and West, or they 
begin so to move when they attain a certain size. This 
migration is a spawning one, for a fair proportion of the 
fish returned were sexually mature. Considering all the 
fish with regard to which full information is available, 
we find that the curve of length-frequency shows two 
modes, at 29 and 37 cms. The range of length is 
therefore that of mature fish, and the probable conclusion 
is that plaice reared off the coasts of Lancashire and 
North Wales migrate either to the South and West of 
St. George’s Channel in order to spawn, or they migrate 
to the ‘‘ Bahama Bank’’ area off the North-East of Isle 
of Man for the same purpose. It is difficult to say yet 
which migration path predominates, but it is probable 
that it 1s the former one. 
(2) Plaice marked and liberated in Cardigan and 
Carnarvon Bays behave similarly with respect to these 
longer migrations, moving either towards the Hast coast 
of Ireland or the Bristol Channel. Thus the mean 
length of the fish hberated there and recaptured in situ 
is 26 cms., while that of the plaice which have emigrated 
out from these Bays to the West and South is 30°5 ems. 
The mean length of the plaice originally set free in the 
Welsh bays, and which have been recovered from off the 
coast North from Anglesey, is 245 cms. Thus there is a 
segregation of the fish with respect to their sizes and 
their migration paths. There is no record of a plaice 
liberated in the Welsh bays migrating to the Bahama 
Bank area. 
(3) Migrations of plaice from the eastern part of the 
Trish Sea to either the North (Firth of Clyde and Solway 
and Isle of Man), to the East and South-East coasts of 
Ireland, and to the mouth of St. George’s Channel and 
the Bristol Channel, are therefore numerous enough in 
