282 MARKETABLE BRITISH MARINE FISHES 



coal-fish, but the hake although its lower jaw scarcely projects at 

 all feeds chiefly on surface fish such as pilchard, herring and 

 sprat. 



The eggs of the fishes of this family are all of the buoyant 

 kind, with the single exception of the burbot, whose eggs are shed 

 loose and separate at the bottom of the sluggish fresh-water 

 streams which it inhabits. Apart, however, from the fact that 

 they develop at the bottom of the water the eggs of the burbot 

 are quite similar to those of the rocklings, and these would also 

 sink in fresh water. There is a great similarity between the eggs 

 of the cod family and those of the flat-fish family. All the 

 members of the first group in the list given above (species of the 

 genus Gadus] have eggs in which the yolk is quite simple and 

 without oil globules : these eggs agree in these respects with those 

 of the small-mouthed flat-fishes, plaice, flounder, dab, &c. (species 

 of Plenronectes}. It is almost impossible to distinguish these 

 eggs from one another at the early stages of development ; the 

 only differences among them are slight differences of size, and in 

 some cases even these are wanting. The remaining members of 

 the family all have eggs with a single oil globule, like those of 

 the left-sided flat-fishes, turbot, brill, &c. There are no eggs in 

 the cod family corresponding to those of the soles. 



The larvae are always distinguished by the fact that the hinder 

 end of the gut is situated at a distance from the edge of the fin- 

 membrane. The young in the third or adolescent period have 

 various habits. Those of the rocklings are entirely surface 

 swimmers, having for a time a bright silvery skin like that of the 

 sprat or herring. The young of other kinds are found near the 

 bottom or among the sea-weeds and rocks of the shore. The 

 very young stages of cod, haddock, &c., are often found lurking 

 under the broad swimming bells of large jelly-fishes which are 

 so abundant near the coasts in summer, but when they get a 

 little larger the}- abandon the surface of the open waters and seek 

 the shore and the bottom. The young of cod, whiting, pollack, 

 and coal -fish are all found near the shore in their first year, 

 and a little further out in their second, while those of the 

 haddock, hake, and ling are not found close to the shore, and 

 only exceptionally in moderately deep water ; these species are 

 reared in the deeper and more distant waters. 



