80 Sigurd Johnsen. 
east of Bearen Island (COLLETT 1880)|. Though the species 
seems to thrive equally well under boreal as under Arctic or 
Sub-Arctic conditions, I think the southern occurrence in boreal 
waters must be looked upon as a secondary one owing to the 
Glacial epoch. The species attains its greatest size absolutely and 
on the average in the northern area, is common here even at 
bottom-temperatures as low as +- 1.2° C. and descends to greater 
depths than in the southern area. Further the spawning in the | 
North Sea (according to EHRENBAUM 1909) takes place from 
January to May when the water-temperature is lowest, in oppo- 
sition to its true companion in boreal waters Glyptocephalus | 
cynoglossus which spawns from May to September. In favour 
of the relict theory suggests further evidences taken from the great 
horizontal distribution and the variation of the species. 
COLLETT (1880) has shown that H. limandoides Bloch from 
Europe can not be specifically distinguished from H. platessoides 
Fabr. from Greenland and the Atlantic coast of N. America as 
far south as Cape Cod.  SMITT (1892 I) agrees herein, but 
maintain, however, that two varieties may be distinguished 
viz. jf. platessoides with P. 12—13 and greatest height of body 
more than 35 per cent. of total length, and 7. limandoides with 
P. 10—11 and the greatest height less than 35 per cent. The 
distinction is based upon few specimens and it seems that 
among the Arctic specimens of 7. /imandoides individuals are 
found agreeing with 7. hippoglossoides. COLLETT (1880) has 
given an account of the variation of the number of rays in the 
dorsal and anal fin in specimens of 7. limandoides from the 
Norwegian Coast and other localities. Great as the local variation 
is, there is, however. a marked increase of the average number 
of rays when grouping the material in a series from southern to 
northern localities. In the table on p. 44 I have accounted for 
the variation in the number of rays in the pectoral of the eyed- 
side, the material consisting of 61 specimens mostly from Norway. 
The normal is P. 11, but at Stavanger P. 10 is nearly as common’). 
1). It is noteworthy that the tendency to a low number was more 
pronounced than the table shows. In the 16 cases of P. 11 the last (i. e. 
the most ventral) ray P,, presented different stages of reduction, being quite 
rudimentary in zbout half of the specimens. 
