ARCTIC ir.itUNDEUS. 



40^ 



north of North Aiiieric;i, the second nortli of Asi;i, and 

 the third straight across tlic Athintii'. The first two 

 gaps tivv tilled, at least in part, li\- the variet}' /'/. 

 (jlacialis, -which seems to ha a, purely Arctic form, while 

 /'/. rirafricnsiis, of the Wiiifc Sea and tiie coast of 

 Alaska, lives in a comparativel}' milder Arctic climate. 

 ( )n tlie west coast of the United States the geographical 

 range of the latter species extends much further south, 

 in common with that of several other Arctic species, 

 which, on account of the set of tlic ocean-currents, may 

 there appear in much more southern latitudes than on 

 the east side of the Atlantic. 



Though J'Icuronectes (jladalis has not heen found 

 within the triu' limits of tlie Scandinavian fauna, in 

 spite of the fact that it lives in their innnediate vici- 

 nity, still it is of especial interest from a systematic 

 point of \iew, as the relations l^etween its two forms 

 throw a considerable light on those between tlie Floun- 

 der and the Plaice. As it is also easier for us in this 

 wav to i;ain a s'encral view of tlie i-elation l)etween 

 these species and tiic Dali, we lici-e give a table of 

 averages tor tlie most important characters of these 

 five forms: 



rilis table, whicli also contains the appreciable i higher than in PI. flesus, and that where it is lower in 



sexual differences in var. /'/. r/Iacialis (frankllnil), shows 



n the tirst place that in the great majority of cases 



where the percentage in J'L glacialis is higher than in 



/'/. cicafricosus, the percentage in PL platessa is also 



the iirst form tiian in the second, it is also lower in 

 PL platessa than in PI. Jiesns. Thus, in most cases 

 the difference of form in the tirst two varieties runs 

 in the same direction as in the last two species. If 



Maxiimiiii percentage in o^ < 



Minimum ., 



MininiHin ., 



Maximum ,, 



Minimum ,, 



Maximum ,, 



Minimum „ 



Masimum ,, 



Minimum ,, 



Maximum ., 



Minimum ,, 



>raximiim „ 



