144.' BEMAEKS ON TTLE PROPAGATION OF SALMON. 



monidae when young, consists of 1. Red spots ; 2, dark spots ; 

 3, parr markings. Of these, the adult true salmon retains only a 

 few dark spots above the lateral line ; the sea trout retains many 

 dark spots ; the lake trout also retains the dark spots ; the river 

 trout retains the red spots. One species of river trout retains 

 the red spots and the parr markings. 



As regards the dentition, the true salmon retains of the vome- 

 rine teeth only the transverse ones ; the sea trout retains, be- 

 sides these, a single short row of vomerine teeth behind the trans- 

 verse ; in the fresh-water trout of all sorts this mesial row is 

 always double. In the young of all, the dentition is the same. 



The great difficulty in the history of the salmon-fry is to 

 determine the length of time it remains in the river from the 

 time it leaves the gravel, about an inch in length, to the moment 

 when it is about to leave the river for the ocean. This period 

 is limited by some to three weeks or a month ; by others, it is 

 extended to two years. Upon the correct determination of this 

 period rests the solution of the two important questions, namely, 

 the propagation and protection of the salmon. 



THE END. 



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