THE SALT-WATER FISHEEIES OF BOHUSLAN. 187 



2. icWi regard to their vertical distrihution, into 

 a. hottom-Jish, that is, fish which always, or the greater part of the 

 year, hve near the bottom. With regard to the cliaracter of the 

 bottom, we can again distinguish among these Jish which live on 

 clayey bottoms, and Jish which live on roclcy or stony bottoms, on 

 lanlis or on the slopes extending from the coast to the great deep,-"^^ 



and 



h. surface-fish, that is, fish which generally live near the surface of 

 the water. 



C— With regard to the degree of regularity with which 



FISH MAKE THEIR APPEARANCE, AND THE EXTENT OF TIME 

 AND SPACE OF THEIR PERIODICAL APPEARANCE, FISH MAY 

 BE DIVIDED, INTO 



1. Stationary fish, which live always in the same locality. 



2. migratory fish, fish which only periodically appear in a place with a 



certain degree of regularity. ^^ 



These migratory fish may be subdivided 

 a. with regard to the direction of the migration or its local object into 



a. fish moving chiefly in a horizontal direction and seeking other 

 waters. These are therefore principally found among the coast- 

 fish, 



/8. fish moving chiefly in a vertical direction and seeking deeper 

 or shallower waters, 



y. fish moving both in a horizontal and vertical direction seeking 

 not only a ditferent depth but entirely different waters. 

 h. with regard to the local object of the migration within a certain 

 given region, into 



a, fish which limit their migrations to this region, and 



^. fish which occasionally extend their migrations farther. 

 c. with regard to the chief object of the periodical migration, into 



a. fish seeking spawning-places, that is, fish which leave their ac- 

 customed dwelling-places principally for the purpose of spawn- 

 ing, and 



/?. fish seeking food,^^ that is, fish which migrate chiefly to seek 

 food, and which, therefore, are less regular, both as to the length 

 and course of their migrations, bexiause the occurrence of food 

 depends on changeable physical conditions. For this reason 

 those fish which visit certain localities for the special purpose 

 of seeking food are occasionally classed in one group with the 

 other migratory fish under the general name of " roving fish" 



**Thi8 would be the place to draw attention to the division proposed by Lorenz (in 

 the above-mentioned place) of the littoral fish into "stationary bottom-fish" and 

 " roving bottom-fish." 



"It is evidently nothing but gross ignorance which has caused a few of our writers 

 on the fishery-question to nse the term "wandering fish" (from the German) instead 

 of the old Swedish term "fly tt Jish:' 



•♦*The term is taken "a parte poiiwi," which is assuredly the desire for food, which 

 is doubtless stronger than a desire for rest and quiet Avell-being. 



