250 ANIMAL SKETCHES. CHAP. xvn. 



cod, and haddock, and rasping away the flesh with the 

 horny teeth, feasts on the juices of its unwilling host. 



The lamprey is the only fish which undergoes a sort of 

 metamorphosis, the young which is called a pride being 

 so different that it used to be regarded as a different genus. 

 The mouth has then no teeth ; but within it there are a 

 number of tentacles ; the eyes are but slightly developed, 

 and there are eight gill-openings. It is used by the 

 fishermen as a bait for pollack. 



Closely allied to the lamprey is another eel-like fish, 

 which is known as the hag-fish or borer. Its habits are 

 very peculiar. It is able to pour out great quantities of 

 slime, for which reason it is regarded by the fishermen as 

 a great nuisance, since it damages their fisheries and 

 interferes with their trade. Mr. Couch states that a single 

 individual, which was placed in about three or four cubic 

 feet of water, poured out so enormous a quantity of slime, 

 that the whole could be lifted out with a stick in a single 

 sheet. But not only by its sliminess does it do harm to 

 the fisherman in his calling. Sometimes at Scarborough 

 a haddock may be drawn up on one of the long lines. 

 From the external view, that is to say, it is haddock, 

 but within it is all hag-fish. For these curious eel-like 

 creatures pass through the gills of recently dead or dying- 

 fishes, and devour the whole of the soft materials inside, 

 leaving nothing but bones and skin. They are the only 

 truly parasitic fishes that we know. 



It must be remembered that these fishes, the lampreys 

 and the hags, eel-like as they are in form, have no true 

 affinities with our little friend the elver. They have no 

 true bones, and no true jaws, and no true limbs. From 

 their circular mouths they are called the cyclostome fishes, 

 and they form a distinct and zoologically exceedingly 

 interesting group. 



