172 THE HAUNTS OF LIFE 



chiefly on herring, mackerel, etc., makes them 

 grow very rapidly, and those that ascend the 

 rivers as " grilse " the following year are often 

 more than double that length. Many of them, 

 however, spend two or three or more years in 

 the sea before they return, and these grow to 

 a great size. Some do not return at all, but 

 remain about the estuaries. It is unlikely that 

 those that do this ever breed ; spawning is 

 only known to take place in fresh water. 



THE STORY OF THE LAMPREY 



One of the most interesting animals that live 

 in fresh-running water is the lamprey. It is 

 not very easy to see, for most of its life is spent 

 concealed in the sand. But at the breeding 

 season it comes out of its hiding-place, and 

 begins to make preparations for the advent of 

 the next generation. 



Let us look for a moment at the lamprey 

 itself. The common brook-lamprey is eel-like 

 in appearance, and, when full grown, is about 

 7 inches long. Its skeleton is gristly instead 

 of bony, like that of the true fishes. It has 

 two fins on the middle line of the back and a 

 tail-fin, but no paired fins. It has no jaws, 



