BULLETIN OF THE UNITED STATES FISH COMMISSION. 173 



from tliese lakes, aud have always found the stomach of the tnountain- 

 trout full of insect larvae, while the stomach of trout contained snails 

 and some young lish, generally the young of the mountain-trout. 



The Iceland lakes which I visited greatly resemble each other, and, 

 })roperly speaking, there are only three which are distinguished from 

 the others, namely, the Myvatn, the Svartarvatn, and the Thingvalla. 

 These three lakes have much in common, particularly the circumstance 

 that subterranean springs will furnish all the year round a supply of 

 evenly warm water, and the many fissures and holes which serve as 

 hidingplaces for the fish, and to a certain extent make up for the lack 

 of vegetation. 



But the lakes have another advantage. I do not refer to the saying 

 so common in Iceland, that all watercourses which spring from lakes 

 containing fish will have fish, because I am inclined to the opinion that 

 the fish rather come from the rivers into the lakes. Some small lakes, 

 however, are of importance to the salmon rivers to which they belong, 

 if the salmon can get up into them or pass them. These lakes furnish 

 a safe place of sojourn for the salmon which during the course of the 

 summer have gone up into fresh water. The remarkably clear water of 

 the streams, their low water at certain season of the year, and the ease 

 with which fishing can be carried on in them, are very dangerous to the 

 salmon when about to spawn and propagate its species. If the salmon 

 can hide in a lake while its sexual organs are apj^roaching maturity, 

 there will be all the more prospect that it will spawn. Such a lake 

 need not be particularly large, and in Iceland a widening of the stream 

 or an inaccessible canyon between the rocks will yield good results 

 which will be still further improved if the bottom contains lava. It 

 will be found that some of the best salmon waters of Iceland show these 

 (tonditions ; as, the Laxa in the Tingore district, the Laxa near Huna- 

 fliot, the Laxa near Kjos, and the Laxji (Ellidara) near Eeikiavik. It is 

 not by accident that these rivers have got the name "Laxa" — salmon- 

 river. The chief fish of economic value found in the fresh waters of 

 Iceland are the salmon, the trout, and the mountain-trout. There is 

 also a variety of the eel which is peculiar to Iceland. Of other fresh- 

 water fish, I might mention the Ga.sterosteus aciikatus, which, however, 

 is of but little importance. 



Both the mountain-trout and the trout are indigenous in the fresh 

 waters of Iceland, and do not leave them — that is, there are tribes of 

 these fish which always remain in the water where they have been 

 hatched and have grown to maturity. But besides tiiese there are 

 tribes, both of trout and mountain-trout, which lor a tin)e stay in the 

 sea, and which go into fresh water onlj' to spawn. It is difiQcult to as- 

 certain how far out to sea they go, but near the Ofiord I have observed 

 all the varieties of the trout and one variety of the mountain-trout, 

 either in the fiord or going up into the streams. I have observed the 

 same in the Southland, and it is nothing strange to see the mountain- 



