The Lakes of Norway. 41 



negotiable by fish ; whereas, before the date of the landslip, 

 a passage was open to Salmonidse vid the fjord, the large 

 river and the rivulet, and these accidents of Nature are the 

 key to the solution of many ichthyological puzzles. 



Landslips and volcanic disturbances have barred the 

 ascent of fish in many a Norwegian river, but it does not 

 necessarily follow that descent is aftected in the same 

 degree, and it is not uncommon to occasionally find a variety 

 of fish in a river which is not general. 



Thus the construction and characteristics of the lakes 

 of Norway are of peculiar interest, telling tales of the past, 

 and providing solutions of problems respecting the species 

 of fish they contain at the present day. 



It should be noted that the fj eld-lakes have not the 

 same facility to free themselves from winter ice as 

 have the rivers ; and, in consequence, they and their 

 inhabitants require more time to attain condition. 



Lakes which communicate with the sea by river and 

 fjord are generally the resort of salmon, sea-trout, and 

 bull-trout for breeding purposes, and it is remarkable that 

 many rivers would be void of spawning redds if it were 

 not for the existence of lakes or lake-like expanses of 

 water at their heads, to which I shall have occasion to 

 refer later on. 



Many of the lakes are situated among the fjelds or 

 higher lands of the country ; but it does not necessarily 



