GREA T BRITAIN,. 1 37 



These young fish have also been observed floating about 

 beneath the harmless disc-shaped Medusa aurita, or secret- 

 ing themselves beneath sea-weeds or other floating sub- 

 stances. Having left the medusae, they roam about for 

 some time, but being pursued by sea-birds and other 

 fishes, they seek a more stationary mode of life near the 

 coast, where, however, young pollack have generally pre- 

 viously established themselves. As they grow in size, they 

 igrate into deeper waters, and at the age of one year they 

 re known as Algae fish by the fishermen, because they 

 esort to sandy localities among the algae near the outer 

 oast, at a depth of twenty or thirty fathoms. These very 

 oung are of all different shades of colour, from bright red 

 r yellow, if residing among the Laminaria, to a bright 

 reen or gray if in more open or sandy places. The very 

 young cod-fish are genuine ground-feeders. Respecting 

 the rapidity with which these fish increase in size, opinions 

 are divided, but at the Southport Aquarium, some of f Ib. 

 in weight increased, in about sixteen months, to 6 or 7 Ib. 

 each (Jackson). 



Hermaphrodites have been recorded by Yarrell (Proc. 

 Zool. Soc. 1845, p. 91) and Dr. J. Smith (Proc. Roy. Phy. 

 Soc. Edin. 1864-65, p. 300, and vol. iv., 1870, p. 256). 



Diseases. I have already alluded to affections of the 

 spinal column, blindness, and parasites in the cod. When 

 out of season they are tormented with sea-lice, while the 

 Lernea branchialis is usually found attached to the gills. 

 When hooked, the borer or myxine, having obtained 

 entrance through its mouth or gill openings, will almost 

 devour its interior, leaving little but the skin remaining. 

 Off the Shetland sandbanks a sessile-eyed crustacean, 

 locally termed " bees," ALga tridens, has been observed to 

 behave in the same manner among fish hooked on the 





