162 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxi. 



Family I. PLEUKONE(^TID^.. 



FLOTTNDERS; HIRAME OR KAREI in Japanese. 



Body strongly compressed, oval or elliptical in outline; head unsj^m- 

 metrical, the cranium twisted, both eyes being on the same side of the 

 body, which is horizontal in life, the ej^ed side l)eing uppermost and 

 colored, the blind side lowermost and usuall}^ plain. In the very 

 young fish the bones of the head are symmetrical, one eve on each side, 

 and the body is vertical in the water. In most species the cranium 

 becomes twisted, bringing the upper eye over with it. P]yes large, 

 well separated; mouth small or large, the dentition various, the teeth 

 always present; premaxillaries protractile; no supplemental maxillary 

 bone; pseudo-brancln^y present; gills 4, a slit behind the fourth; lower 

 pharyngeals separate; no air-bladder; preopercle with its margin usu- 

 ally distinct; not wholly adnate or hidden by the skin of the head; 

 vent not far behind head, the viscera confined to the anterior part of 

 the body; scales various, rarely absent, usually small; lateral lines 

 usuall}" present, extending on the caudal fin, sometimes duplicated or 

 wanting. Dorsal fin long, continuous, of soft rays only, beginning on 

 the head; anal similar, shorter; caudal various, sometimes coalescent 

 with dorsal and anal; pectorals inserted rather high, rarel}^ wanting; 

 ventrals thoracic under the pectorals, usuall}^ of several soft rays, one 

 of them sometimes wanting. Fishes mostly carnivorous, inhabiting 

 sandy bottoms in all seas, some species ascending rivers. 



Most of the flounders are valued as food, the flesh being Avhite 

 and wholesome, but rather tasteless, and in some species somewhat 

 coarse. These fishes are known in Japanese as Karei, usually with 

 an adjective prefix, indicating the different species, as Kurokarei, 

 black flounder; Mizugarei, water flounder; Ishigarei, rock flounder. 

 The larger ones are called Hirame or halibut {Idra^ broad; ina^ eye). 



Apparently the members of the Psettina3 or Turbot tribe are 

 more primitive than the other subfamilies represented in Japan. The 

 relative simplicity of structure in the Halil)ut tribe is of the nature 

 of degeneration. 



The earliest fossil flounders, from the European Cretaceous, are 

 related to the genus ^o^A^^s, which contains the Brill, Bothus I'Jiomhus^ 

 an ally of the Japanese genus, PlatophryK. 



KEY TO SUBFAMILIES OF PLEI'RONECTID.E. 



A. Ventral fins unsymmetrical, dissimilar in position and usually also in form, the 

 ventral fin of the eyed side being extended along the ridge of the abdomen. 



Eyes and color on the left side. (Turbot tril)e) Psettin.k, I 



AA. Ventral fins symmetrical, similar in position and in form of base, the ventral 

 of the colored side not -extended along the ridge of the abdomen. 

 a. Mouth nearly symmetrical, the dentition nearly equally developed on both 



