CLASS OF FISHES. 353 



the coast, and give rise to important fisheries. The salmon 

 is equally remarkable for its voyages. Its precise Jialitat 

 in the ocean is unknown ; but at stated periods it ascends 

 the rivers even to their sources, in general during the 

 autumn and early winter months. Under the gravel of 

 these fresh-water streams it deposits its eggs, which in early 

 spring, usually about the beginning of May, leave the 

 gravel to pass into the stream. The period intervening be- 

 tween their escape through the gravel, to their descent to 

 the ocean as smolts (that is, young fish covered with silvery 

 scales), has not yet been fully determined, some viewing it as 

 a year, others only a few weeks. But however this may be, 

 there appear annually in May, in every salmon river, vast 

 shoals of smolts, that is, silvery-scaled fishes, and which for 

 certain are the young of the salmon. In a very short time 

 they begin to descend the streams, in which descent they 

 are much aided by a flooded state of the river from rain, and 

 with them descend the spawned fish their presumed parents. 

 The srnolt which descends to the ocean in the beginning of 

 May, and which at that time is four or five inches in length, and 

 one or two ounces in weight, returns in June and July a well 

 grown salmon of five or six pounds. Thus, if the growth 

 of young salmon in fresh waters be slow, their growth in the 

 sea, where they seem to obtain a peculiar kind of food, is 

 rapid beyond imagination. During the winter, the fish that 

 are about to spawn, and that have spawned, do not seem to 

 feed ; they lose weight constantly, and return to the sea in 

 May, generally in an extremely exhausted state. Like 

 swallows, salmon have the instinct of returning to the place 

 of their birth, a fact known from the most remote times, 

 and proved by a vast number of experiments made in Scot- 

 land during the last half century. The average period of the 

 incubation of the egg under the gravel is about one hundred 

 and twenty days ; they incubate only during the winter and 

 spring, and the young salmon, whilst in the rivers, has 

 generic characters and a dentition common to all the sal- 

 monidje. R. K. 



493. The habits of fishes do not oifer many curious 

 particulars ; nevertheless, reflecting on their importance, but 

 a few years ago in the history of the maritime nations of 

 Europe, and that in France there are from thirty to forty 

 thousand seafaring men still engaged in this branch of in- 

 dustry, extending their voyages to the coasts of Iceland and 



