NORTH SEA INVESTIGATIONS. 137 



1 used it in distinguishing the and 1 groups of plaice before Petersen 

 had published anything concerning the growth of this species. Thus, 

 Petersen says that my specimens in January, April, and May are 

 explained by me as the fry of the year, but that they are the smallest 

 specimens of a group reaching to 2, 3, 4, and 5 inches in length. Now 

 a reference to my data on p. 347, Vol. II. of this Journal, will show that 

 the greatest number of my specimens from the Humber at the end of 

 April were 2 in. in length, while those of 3 and 4 inches were in very 

 small numbers. I find it impossible to believe that these large 

 numbers of plaice at 2 in. were over a year old, while the few of 3 

 and 4 inches were regarded by me as the smallest of the brood of 

 the previous year. Petersen accepts my identification of the specimens 

 mostly 2| in. long in June as belonging to the group, though he says 

 they were about IJ in. long, which is not correct. As to the absence 

 of such specimens in May, which Petersen thinks supports his view, 

 it was merely due to the fact that Mr. Holt did not collect any in 

 that month. 



With regard to the 1 group, or specimens in their second summer, 

 Petersen considers that the specimens I assigned to this group, 8 to 

 12 in. long, from Arlberg (which he quotes as Esbjerg, Arlberg being 

 apparently a misnomer) were over 2 years old. In his tables the 1 

 group in the Cattegat, in May and June, are only 3 to 5 inches long. 

 The fish in the Cattegat appear to be considerably smaller than in the 

 North Sea, and I certainly still believe my own estimates to be correct 

 for the sizes at which the greatest number of individuals are found. 

 Thus, in March, at the mouth of the Humber, the majority of plaice 

 taken by the shrimp trawls were 7 to 8 in, long, and as far as the 

 evidence goes the number of specimens between this and 2 in. are com- 

 paratively fewer. In May and June the mid-size of the fish brought 

 from Schiermonnikoog and the Danish coast to Grimsby, is 9 or 9i in. 

 If the fish in their second year were mostly 4 or 5 in, long in summer, 

 these fish would necessarily be more numerous than those of 8 or 9 in. 

 long, a supposition which is against all the evidence we have at 

 present. 



Petersen states that he marked 1000 specimens of plaice in the 

 Limfjord, 7 to 10 in. long, in March and April, 1893, and they were 

 from 13 to 14 in. long in October and November. They grew, therefore, 

 4 to 6 in. in length in 6 to 8 months, and yet he believes that at 7 

 to 10 in. they were 2 years old. It is certain that fish grow slower 

 as they get older, so that it is almost impossible to believe that a plaice 

 which could grow from, say, 8 to 13 in. in 7 months, should rei^uire 



2 years to reach the length of 8 in. 



I think, then, that we have very strong evidence that the smaller fish, 



L 2 



