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THE BOOK OF NATURE STUDY 



in length. They are carnivorous, and sometimes fix themselves 

 to fishes, e.g. salmon, by means of their suctorial mouths, using 



a piston-like " tongue " with horny teeth 

 to scrape a hole in their victims. In 

 spring they ascend the rivers to spawn, 

 and may sometimes be seen making their 

 way up stream. From a bridge one may 

 sometimes see a lamprey resting at the 

 bottom with its mouth fastened to a 

 stone. The eggs are laid in the gravelly 

 bed of the river, and thereafter the 

 parents turn towards the sea, sometimes, 

 at least, dying before they reach it. 

 The young remain in the rivers for three 

 or four years. 



The river lampreys are smaller ani- 

 mals, from a foot to a foot and a half 

 in length. Their habits are similar to 

 those of the sea lamprey, except that, 

 they keep to fresh water and spawn in 

 the smaller streams. They seem to eat 

 a good many insect larvse, worms, and 

 other small fry in the rivers. 



The young lampreys and lamperns 

 differ from the parents in many details, 

 e.g. in the shape of the mouth, in having 

 the eyes unexposed, in having different 

 breathing arrangements, and in feeding 

 on minute particles and microscopic 

 animals. They differ so much from the 

 adults that they were known for a long 

 time by a different name Ammoc&tes. 

 They remain in this larval state for three or four years, but in 

 their third or fourth winter they undergo a rapid change and don 

 the adult characters. The mouth becomes funnel-shaped and 

 acquires horny teeth ; the eyes reach the surface ; there are 

 various deep-seated changes, and the creatures become car- 

 nivorous. The name " niner " or " nine-eye " (German, Neun- 



