37^ 1-L.\TFISHES (HF.TEROSOM.\T.\) 



ridge prominent, rugose, terminating in a rounded protuberance above operculum, 

 behind which is a smaller prominence on the post-temporal. Maxillary extending 

 to below anterior edge or anterior part of eye. length on ocular side 4 to 4J, on blind 

 side J J to 4 in that of head : lower jaw a little projecting, about 3 in head ; dental 



formula ^^ X — "L-Z — , 7 to 9 gill-rakers on lower part of anterior arch; lower 



4-16 + 15-22 

 phars-ngeals massive, rather broad, width about 3 in length ; teeth of inner edge 

 of each pharj'ngeal 4 or 5 in number, large, rounded or flattened ; those of outer edge 

 similar but smaller, 7 to 10 in number ; 5 or 6 more compressed teeth with truncated 

 tips along hinder margin : several teeth, similar to those of the outer row, between 

 the three principal rows. Scales in the male feebly imbricated, at least on ocular side, 

 scarcely imbricated and largely embedded (at least anteriorly) in the female ; in the 

 male the scales are mostly ctenoid on both sides of body, but in the abdominal region 

 of the blind side they tend to be cycloid and embedded ; in the female the .scales are 

 nearly all smooth or rather feebly ctenoid, but narrow strips of distinctly ctenoid 

 scales are present at upper and lower edges of body ; head generally entirely naked 

 on blind side ; 73 to 76 pores in lateral line. Lateral line rising a little or with a very 

 low curve above pectoral fin. Dorsal 52-59 ; origin above anterior half or middle 

 of eye ; highest rays 2 to i\ in length of head. Anal 39-42. Pectoral of ocular side 

 with 10 or II (occasionally 12) rays (i to 7 branched), length 1} to 2 J in head (about 

 twice in the male). Pelvics with 6 rays. Caudal with 18 rays (12 branched), rounded 

 or subtruncate ; caudal peduncle as long as deep or a little deeper than long Brownish 

 or blackish, without distinctive markings ; fins paler, sometimes with traces of 

 darker spots. 



Type. — Zoologisches Museum der Universitiit I3erlin ('). 



Distribution. — Arctic shores of Russia, Siberia and .Maska ; .\rctic North 

 America : entering fresh water. 



Specimens Ex.\mined : 



Stanford Univ. 

 U.S. Nat. Mus. 



Two forms of this species may be recognised, differing from one another in the 

 shape of the body. Among the specimens listed above, deep-bodied examples occur 

 in Arctic America and in Kolguev Isd., north-east of the White Sea: slender-bodied 

 examples in Alaska and the Pacific coast of Siberia. According to Smitt. however, 

 the slender form is common in the White Sea. and the specimen of dwinensis figured 

 bv Lilljeborg is of this type. Both types, therefore, appear to occur together, at 

 least in northern Eurasia, and, for this reason, and because I am unable to detect 

 any constant differences apart from the depth of the body. I have been unwilling to 

 regard these as other than varieties. If it is later found necessary to apply different 

 names to the two forms, the deep-bodied form will stand as glacialis (= franklinii), 

 the slender form as cicatricosits (— dti'inetisis). 



Ssytsch-.Awerinzewa' has recently made an important statistical study of this 

 species in the White Sea. in which she compares the numbers of fin-rays and vertebra; 

 with those found in samples of Platichthys flesw: from the same locality and of 

 Plettronectes platessa from the Barents Sea. 



