906 



SCANDINAVIAN KI.SllK.s. 



li: Leni;th <if the lower jaw loss 

 than tho least depth of the 

 tail 



aa: Length of tlie inaxillaries 

 more than ' , of that of the 

 head and than 36 % of that 

 of the head reduced — Cor. 

 polcur. 



Length of the maxillarics 

 less than ' , of that of the 

 head and than 36 % of that 



Coreyunua polcnr. 



hb: 



of the head reduced — Cor. 

 brach ymy ? t a .\. 



Iiisti'fid of dt\scriVjiiig these fonns at length we 

 .shall refer the reader to the two following- tables of 

 averages, the first intended to show both the difference 

 of form and sex and the changes of growth in the 

 three forms, of which we have examined a sufficient 

 number of male and female specimens of various ages 

 to enable us to trace the last-mentioned chano;es. 



Not even in the averages do \vc here find any 

 constant difference, except in the number of the gill- 

 rakers; and even the form difference which in the 

 case of adult specimens is the most trustworthy di- 

 stinction between hlfisikdr and fcts'il'dr, the different 



depth of the snout, proves to be a character of age. 

 But ill the last-mentioned respect, where the percent- 

 ages rise with age, as well as in other characteristic 

 features, e. g. the relative length of the lower jaw, 

 where the percentages sink with increasing age, we 



