230 Part III — Eighteenth Annual Report 



Table XI. 



Height of Body in Percentage of Body-length. 



Region. 



Sex. 



Immature (250-350mm. ) 



Mature (250-350mm.) 



Mature (350— mm.) 



No. 



M. 



P.F. 



No. 



M. 



P.F. 



No. 



M. 



P.F. 



So. North Sea . 



9 

 + 



146 



61-46 



60-71-62-21 



61 



61-42 



60-52-62-32 



84 



62-00 



6 1 . -15-62-85 







48 



60-75 



59-40-62-10 



115 



60-76 



59-91-61-61 



76 



61-42 



60-47-62-37 



Aberdeen . . 



2 



61 



65-64 



64-44-66-84 









28 



66-18 



65-48-67-88 







65 



65-48 



64-28-66-68 



51 



6477 



63-37-66-17 



36 



63-90 



62-50-64-30 



Baltic . . . 



2 









30 



62-27 











There seems to be no other conclusion but that this difference arises 

 from the presence of distinct races in the North Sea. Age-, maturity-, 

 sex- and growth-differences are all excluded, and a probability, which 

 amounts to a certainty, declares that the observed differences represent 

 real differences in nature. We should expect, however, that this 

 character would not be the only one to differ, because this difference in 

 height means a difference in mass, and such a difference must be 

 correlated with other differences in structure if the notion of the balance 

 of organs already stated is correct. It will be shown later whether this is 

 the case or not. 



Tail. — It will be seen from the accompanying Table that the length of 

 tail relative to body-length is practically identical in both the northerly 

 and southerly North Sea specimens. Relative to the body-length, there- 

 fore, there seems to be no change in this character from any cause. The 

 Baltic specimens seem a little longer in this respect, although the small 

 number of specimens renders this conclusion uncertain. Duncker did 

 not notice any difference, but he expressed this dimension apparently in 

 percentage of the total length of the fish, and such line differences would 

 not be shown as when the dimensions were taken to the length of body 

 only. An examination of more specimens from the Baltic would there- 

 fore require to be made. 



[Table. 



