230 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [6] 



bb. Mouth uusyinmetrical, the jaws on the eyed side with nearly straight outline, 

 the hones on the hlind side strongly curved ; teeth chiefly on the blind 

 side. 



d. Ventral fins unsymmetrical, that of the eyed side extended along the ridge 



of the abdomen, snout with a free ray or other appendage in connection 

 with the first ray of the dorsal. Eyes and color on the right side. 



ONCOPTFUINiE III. 



dd. Ventral fins nearly or quite symmetrical, that of the eyedside with short 

 base ; eyes and color on the right side (with occasional exceptions). 



Platessin^e IV. 

 aa. Soles. Edge of preopercle adnate, usually obscured by the scales ; mouth very 

 small, much twisted toward the blind side, and with rudimentary teeth ; 

 pectoral and ventral fins generally small, occasionally obsolete. 



e. Eyes on the right side, separated by a bony ridge Solein.e V. 



ee. Eyes on the left side, not separated by a bony ridge.. ..Cynoglossin.e VI. 



ANALYSIS OF GENERA OF PLEURONECTIDJS FOUND IN AMERICA AND 



EUROPE. 



Subfamily L-HIPPOGLQSSIMl. 



( Large-mou thed flounders with the ventral fins symmetrical. ) 



Mouth symmetrical, the jaws and the dentition nearly equally devel- 

 oped on both sides ; gape usually wide, the maxillary more than one- 

 third length of head. Lower pharyngeals narrow, usually with but one 

 or two rows of sharp teeth ; teeth in jaws usually acute. Eyes large ; 

 edge of preopercle free. Pectoral and ventral fins well developed, the 

 ventral fins similar in position and in form of base, the ventral fin of the 

 eyed side not beiug attached along the ridge of the abdomen. Septum 

 of gill cavity without foramen. 



a. Vertebrae and fin-rays much increased in number (the vertebra? about 50, the dorsal rays 

 about 100, the anal rays about 85) ; body comparatively elongate ; 

 caudal fin lunate; lateral line simple; anal spine mostly obso- 

 lete. Dextral species, Arctic in distribution.. (Genera allied to 

 Hippog loss us. ) 

 c. Large teeth'm both jaws arrow-shaped, biserial. some of them depressible^ upper 

 eye with vertical range ; gill-rakers short ; scales deciduous, cili- 

 ated ; lateral line without arch ; flesh soft. Vertebras (stomias) 



12+37 = 49 Atheresthes, 1. 



cc. Large teeth not arrow-shaped, biserial above, uniserial below ; scales very 

 small, cycloid ; gill-rakers long and slender; eyes strictly lateral. 

 d. Lateral line without anterior arch; lower pharyngeal teeth uniserial. 



Platysomatichthys, 2. 

 dd. Lateral line with an interior arch; lower pharyngeal teeth biserial ; vertebral 



( h ippoglossus) 16+34=50 Hippoglossus, 3. 



aa. Yertebrw and fin-rays in moderate number (vertebra less than 46, dorsal rays less 

 than 95, anal rays less than 75) ; caudal fin double truncate or 

 rounded, the median rays longest. 

 /. Lateral line without distinct anterior arch ; vertebra?, 40 to 46 ; body nor- 

 mally dextral ;* caudal peduncle distinct ; scales ciliated ; anal 

 spine usually strong. Species of subarctic distribution. (Genera 

 allied to Hippoglossoides.) 



'Frequently sinistral in Hippoglossoides elassodon. 



