89 



be most interesting, but this calls for very exhaustive experi- 

 mental and observational work. 



We think there are two sources of the plaice eggs that are 

 found in the plankton of the Irish Sea : (1) somewhere to the 

 S.W. in St. George's Channel, and (2) the grounds near the 

 entrance to the Solway Firth. The reason for attributing by 

 far the larger share of plaice eggs to the St. George's Channel 

 grounds is the direction of the tidal streams in this area and 

 in the Irish Sea. The flood-stream sets in a northerly direction 

 in St. George's Channel, with indraughts into Cardigan and 

 Carnarvon Bays. It clings strongly to the Anglesey promon- 

 tory and then sets towards the East, round into the Liverpool 

 Bay area. Near a line crossing the Irish Sea from Morecambe 

 Bay to about Ramsey the northerly flowing flood-stream 

 slackens, and there is a general tendency for the drift of 

 wreckage and other floating objects to be arrested on the 

 North Lancashire and Cumberland coasts, between Morecambe 

 Bay and about Drigg, in Cumberland. The ebb-stream runs 

 in nearly the opposite directions, but there is also a general 

 tendency to a drift from South to North, so that more water 

 enters the Irish Sea with the flood-tide from the South than 

 leaves it with the ebb-tide. Approximately the whole contents 

 of St. George's Channel and the Irish Sea are changed every 

 year, the water flowing out through the North Channel and 

 entering by the South. 



Plaice eggs spawned in St. George's Channel will, therefore, 

 tend to drift slowly to the North and East, round Anglesey, 

 into the shallow-water region between the North Coast of 

 Wales and the " head of the tide," between Morecambe Bay 

 and Ramsey, in Isle of Man. 



Such a southerly spawning area is thus to be deduced from 

 a knowledge of the eft'ect of the tidal streams, but it has yet to 

 be actually observed. The existence of northerly spawning 

 grounds has long been asserted by the trawlers. It is said 



