THE COD FAMILY AND THE SAND-EELS 263 



regarded as the commonest kind in British seas, particularly 

 in the western half of the English Channel, where specimens 

 of at least 18 in. are taken. The very young examples of 

 this and other rocklings are popularly known as " mackerel- 

 midge," because the mackerel greedily devour them at the surface 

 of the sea in summer weather, dashing through almost solid 

 masses of the fry. These young rocklings have been variously 

 named and described, like the young of some other fishes, as 

 species distinct from the adults. 



The five-bearded rockling is brown above and lighter on 

 the under surface. As its name denotes, there are five barbels 

 in all, the longest on the chin, the other four on the snout. 

 The teeth in the jaws and vomer are long and pointed, and the 

 fish probably feeds, for the most part at night, on small fishes, 

 molluscs, and crustaceans. In its search for food it is aided not 

 alone by the barbels, but also by the very sensitive organs of 

 touch in the pelvic fins. 



What was said on an earlier page in respect of the import- 

 ance of studying the life-history and movements of some of the 

 smaller fishes on which those of greater moment to ourselves 

 feed is well illustrated by the rocklings. In their young, 

 silvery, surface-swimming stage they form the food of 

 mackerel, and at a later stage, when their residence is at the 

 bottom of the sea, they are the prey of ling and conger. 



The five-bearded rockling spawns during summer, from 

 April to August, and its egg and development were studied by 

 Mr. G. Brook,* who pointed out the error of Cornish in 

 describing the buoyant egg of this fish as deposited in a coral- 

 line nest in the rock crevices. A floating egg could obviously 

 not develop in a nest under water, yet the mistake was long 

 accepted. According to the accurate observer named above, 

 the egg of the five-bearded rockling measures rather over -^ in. 

 in diameter, is oval in shape, and so fragile that the least pres- 

 sure disturbs its outline. Mr. Brook found the egg hatch out 

 * Set/ourn. Linn. Soc, 1885, Vol. XVIII., pp. 298-307. 



