380 ' EXAMINATION OF THE PRESENT STATE 
Grimsby, I have been able in this way to examine the small plaice 
caught on those grounds during the spawning season, and indeed to 
compare them with spawning fish consigned at the same time from 
the Baltic. There can be no possible doubt of the distinctness of 
the two types, nor of the immaturity of the small fish caught on the 
Eastern grounds of the North Sea. 
The lemon sole or cock sole (Pl. microcephalus) agrees with the 
true sole in that some females are mature at only 10 inches, but I 
think 12 inches is the length usually attaimed before the assumption of 
maturity. 
As to the size at which the halibut commences to spawn I have no 
conclusive information. The fish is not now of much importance in 
North Sea trawling, on account of its scarcity, and the same reason 
makes it difficult to procure sufficient material to establish a North 
Sea standard. Plenty may be had from Iceland or Farée, but the 
species reaches a larger size in the higher latitudes, and presumably 
attains a larger size before spawning than is the case with natives of 
the North Sea. I think my provisional limit of 36 inches is really 
considerably below the mark for any district inhabited by this fish. 
With regard to cod, the opinion is held by fishermen that there 
are several distinct varieties within the limits of the North Sea, and 
in Norway Captain Dannevig holds a similar belief most strongly. I 
have had neither the leisure nor the inclination to investigate the 
matter for myself, and consider that, so far as practical purposes are 
concerned, the existence or non-existence of such varieties 1s of no 
moment, as there could be no possibility of discriminating between 
one and the other unless every fishery official were a trained naturalist. 
The proposed standard of 25 inches can certainly not be regarded as 
too high; and, if varieties exist, it 1s applicable to the smallest. 
Many cod undoubtedly reach a considerably larger size before 
spawning. 
Before we leave the question of sexual maturity, I must advert 
briefly to the inquiries on the same subject which were carried on 
by my colleagne Mr. Cunningham, contemporaneously with my own, 
in the Plymouth district. * 
The results are most interesting, since they show conclusively that 
very great difference may exist in different districts in the size at 
which sexual maturity is attained by a species. This difference, 
as Mr. Cunningham justly observes, is a corollary of a difference in 
the maximum size attained by the species in either district. 
Thus the plaice on our South-west Coast are considerably smaller 
than North Sea forms, and Mr. Cunningham considers the biological 
* Vide lis paper, Journ. Marine Biol. Assoce., vol. iii, p. 64. 
