50 



but in all cases the bays to the north of the southern half of the 

 district receive the greatest numbers. The invasion begins about 

 May, and the wave of arrivals gradually increases until the latter 

 part of August when the return to deeper water begins. They 

 leave the inshore waters finally about October or November. The 

 sizes most in evidence from the results of the trawling are 14 to 

 to 28 cm., but even the predominant sizes during the season pass 

 gradually from 15 or 16 to 18 cm., and at the end of the season 

 only a few large gurnards still occupy the bays. As with the other 

 species considered therefore the summer immigration consists 

 mainly of young immature fish, which are joined by a number 

 of spent fish after the spawning season. 



But there is a difference. Normally and usually the dabs 

 increase in numbers towards the south, reaching a maximun at 

 Cambois. The gurnards are most numerous at Alnmouth and 

 Druridge, and tail off to the south. The distribution is therefore 

 more like that of the plaice ; the difference is that instead of the 

 headquarters being in the neighbourhood of Holy Island it is in 

 the region of Coquet Island. 



This is borne out by a consideration of the school of gurnards 

 of the Scottish waters adjacent. It has its headquarters to the 

 east of the coast of Fifeshire, and tails off to the south in the Firth 

 of Forth, and we evidently do not meet another school to the 

 south of the Forth school until we come to that of the Northum- 

 berland coast. It appears to be obvious therefore that in the 

 case of the gurnard we have schools derived from isolated spawn- 

 ing assemblages. The spawning season is April to August, and 

 the eggs are pelagic. In the case of the Scottish school just 

 mentioned, the spawning ground must lie to the north-east of 

 the area which receives the bulk of the " " group, and in that 

 of the Northumberland school to the north-east of the Fame 

 Islands. In each case the products of the spawning are assembled 

 on a recruiting ground, and move inwards to gain a position in 

 shallow water. There they are joined during the next summer 

 by the older groups and spent fish, especially by the immature, 

 which have immediately preceded them as occupants of the region. 

 These come into the shore region each summer in an ever increas- 

 ing crowd ; and during each season the mean size of the pre 

 dominant migrants gradually increases. This may be in some 



