FLAT-FISHES. 555 



frequently, in a vertical position. Only one species is known, 

 Ps. erumei, common in the Indian Ocean. 



HiPPOGLOSSUS. — Eyes on the right side ; mouth wide, the 

 length of the maxillary being one-third of that of the head. 

 Teeth in the upper jaw in a double series ; the anterior of the 

 upper jaw and the lateral of the lower strong. The dorsal fin 

 commences above the eye. 



The "Holibut" (II. vulgaris) is the largest of all Flat- 

 fishes, attaining to a length of five and six feet, and a weight 

 of several hundredweights. It is found along the northern 

 coasts of Europe, on the coasts of Kamtschatka and Cali- 

 fornia, particularly frequenting banks situated at some 

 distance from the coast, and at a depth of 50 to 120 fathoms. 



Other genera, with nearly symmetrical mouth, in which 

 the dorsal fin commences above the eye, are Hippoglossoides 

 (the " Eough Dab ") and Tcpliritis. 



Rhombus. — Eyes on the left side. Mouth wide, the length 

 of the maxillary being more than one-third of that of the 

 head. Each jaw with a band of villiform teeth, without canines ; 

 vomerine teeth, none on the palatines. The dorsal fin com- 

 mences on the snout. Scales none or small. 



Seven species from the North Atlantic and Mediterranean, 

 of which the most noteworthy are the " Turbot," Rh. maximus, 

 one of the most valued food-fishes, and growing to a length 

 of three feet ; the " Turbot of the Black Sea," Eh. mavticus, 

 the body of which is covered with bony, conical tubercles, 

 which are as large as the eye ; the " Brill," Bh. Imvis, repre- 

 sented on the North American coasts by Bli. aquosus ; the 

 " Whiff," or " Mary-sole," or " Sail-fluke," Rh. megastoma ; 

 " Bloch's Top-knot," Rh. pundatus (described by Yarrell as 

 Rh. hirtus, and often confounded with the following species). 



Phrynorhombus, differing from Rhomhus in lacking vomer- 

 ine teeth. The scales are very small and spiny. 



The " Top-knot " {Ph. unimaculatus) occurs occasionally 



