234 "PERFECT-MOUTHED" FISHES 



the lower. The skin is devoid of scales, and is normally dark 

 above and light beneath the body, though some congers have been 

 caught that are of a pale colour all over. Females grow to 6 or 7 

 feet in length as a rule, though larger ones are occasionally taken 

 the males are much smaller. 



Altogether about 150 species of eel are known, inhabiting fresh 

 water, estuaries, the sea coasts, and, in some cases, the depths 

 of the ocean down to 2,500 fathoms. Some of the deep-sea forms 

 are very remarkable. One called the "Snub-nosed" Eel has a 

 short head with thick lips and huge protruding teeth, distinctly 

 like a bulldog's in character ; in other forms frequenting the abysses 

 of the ocean the jaws are prolonged and needle-like. 



The Flat-fishes (Pleuronectida) are ground fishes, abundant 

 along almost all coasts except in extreme northern and southern 

 regions. Those inhabiting the tropics are of little value as food, 

 but in temperate regions the flat-fishes are amongst the most 

 valuable of marketable marine fishes. The chief species found 

 in British waters are Turbot, Halibut, Plaice, Flounder, Brill, Sole, 

 Lemon-Sole, Dab, Witch, and Megrim. 



Flat-fishes are chiefly remarkable for being unsymmetric 

 that is to say, they habitually lie upon one side, and both eyes 

 situated on the side of the fish that is uppermost ; in addition, 

 the mouth of many species is twisted and lop-sided. Some members 

 of this family are clothed with scales having a spiny margin ; in 

 others the scales are rudimentary, or they may be represented 

 by rough tubercles on the skin. The paired fins are usually very 

 small (in some cases altogether absent), the tail fin but little 

 developed, the dorsal and ventral fins very long, without spines, 

 the dorsal fin often extending on to the head along the edge 

 and not between the eyes. 



Some species habitually lie on the right side of the body, others 

 on the left. The side which rests on the ground is white, the 

 uppermost side coloured light brown, dark brown, or black, and 

 often marked with spots or splashes of yellow, orange, or red. 

 The dull sombre hues of these curious fishes are in a great measure 

 protective, as when in their usual position lying flat upon the 

 ground at the sea-bottom their presence is not easily detected ; 

 moreover, they possess in a remarkable degree the power of chang- 

 ing their colour to suit their surroundings. Thus on light, sandy 



