50 



MARKETABLE BRITISH MARINE FISHES 



they have the throat fins rudimentary or absent, and a single 

 long dorsal and ventral. They burrow in the sand near shore. 

 They occur on the coasts of Europe and America, and there 

 are two British kinds, the larger sand-eel and the smaller. 



The flat-fishes (Fig. 14) are the most remarkable of all 

 fishes in structure, because the surface on which they lie on the 



Fig. 14. — The Plaice. 



ground is one side of the body, either the right or the left 

 according to the species, and both eyes are on the upper side : 

 the upper side also is coloured, the lower side white and without 

 pigment. There is a long dorsal and long ventral extending 

 nearly from head to tail. No flat-fishes are found in the great 

 depths of oceans, but they are abundant in the tropics, and 

 along all coasts except those of the extreme north and south. 

 The tropical kinds are different from those of temperate regions, 

 and are for the most part useless as food. The principal 

 species in British waters are the plaice, flounder, dab, witch, 

 lemon dab (called usually lemon sole), halibut, long rough dab, 

 sole, turbot, brill, and megrim. 



The third great division of the bony fishes has, like the 

 second, a closed air-bladder and the pelvic fins in the front part of 

 the body, but many of the fin rays form strong stiff spines, and 

 spines are often largely developed on the head and body. This 

 division contains a great variety of forms, classed by naturalists 



