814 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 



similar, shorter ; caudal various, sometimes coalescent with dorsal and 

 anal; pectorals inserted rather high, sometimes wanting; ventrals 

 under the pectorals, usually of several soft rays, sometimes wanting. 

 Fishes mostly carnivorous, inhabiting sandy bottoms in all seas, some 

 species ascending rivers. Many of them are imi)ortant food-fishes. 

 Genera about 40 ; species nearly 400. 

 (Plewronectidcr, Giiutlier, iv, 399-504.) 



a. Pectoral and ventral fins botli present ; caudal distinct ; margin of proopercle more 



or less free. 

 &. Mouth large; teeth nearly equally developed on both sides of the mouth, 

 c. Ventral hn of the left side inserted nearly on the ridge of the abdomen ; body 

 sinistral. 

 d. Vomer with teeth; lateral line arched in front ; scales small or obsolete. 



BoTHUS, 449. 

 dd. Vomer toothless; lateral line not arched; scales well developed, mostly 



ciliated Citharichthys, 450. 



cc. Ventral fins both lateral ; vomer and palatines toothless. 

 e. Caudal lin lunate. 



/. Lateral line arched in front; scales cycloid HiPPOGLOSSUS, 451. 



ff. Lateral line not arched. 



g. Teeth not arrow-shaped ; gill-rakers few, short. 



Platysomatichthys, 452. 

 gg. Teeth arrow-shaped; gill-rakers numerous, long. 



Atheresthes, 453. 

 ee. Caudal fin not lunate, the middle rays produced. 



h. Lateral line arched in front; body usually sinistral. 



Paralichthys, 454. 

 hh. Lateral line not arched ; body dextral. 



HiPPOGLOSSOIDES, 455. 

 ih. Month small; teeth, if present, most developed on the blind side. 



j. Teeth small, acute, in several series; lateral line nearly straight, 

 with an accessory branch ; scales small, cycloid ; 

 eyes dextral. 

 Jc. Lips longitudinally plicate; dorsal fin beginning on the blind 



side Pleurontchthys, 45G. 



kk. Lips simple; dorsal fin beginning on the median line. 



.Hypsopsetta, 457. 

 jj. Teeth in one series. 



I. Teeth rather large, bluntish or trenchant ; eyes dextral (some- 

 times sinistral inonespecies) ; ventrals (usually) both 

 lateral, 

 m. Dorsal fin with less than 80 rays; anal with less than 60. 



Pleuroxectes, 458. 

 vim. Dorsal fin wi th more than 95 rays ; anal with more than 80; 

 body unusually elongate. 

 n. Left side of skull with strong mucous cavities; anal spine 



present Glyptocephalus, 459. 



nn. Left side of skull without conspicuous mucous cavities; 



anal spine obsolete C ynicoglossus, 480. 



II. Teeth small, acute, in one series; lateral line nearly straight, 

 simple; scales thin, ctenoid; eyes sinistral; left ven- 

 tral on ridge of abdomen Etropus, 461. 



