242 THE ANGLEK-NATUKALIST. 



May or early in June and thereupon go down to the sea, 

 they remain as Parrs another year; and without Smolt 

 scales they will not migrate, and cannot exist in salt water. 



8. The length of the Parr at six weeks old is about an 

 inch and a half or two inches ; and the weight of the Smolt 

 before reaching the tidal wave from one to two ounces. 



9. In at least many cases, Smolts thus migrating to the 

 sea in May and June return as Grilse, sometimes within 

 five, generally within ten weeks, the increase in weight 

 during that period varying from 2 to 10 Ibs., the average 

 being from 4 to 6 Ibs. ; and these Grilse spawn about 

 November or December go back to the sea and (in 

 many cases) re-ascend the rivers the next spring as Sal- 

 mon, with a further increase of from 4 to 12 Ibs. Thus, 

 a fish hatched in April 1854, and marked when migrating 

 in May 1855, was caught as a Salmon of 22 Ibs. weight 

 in March 1856. 



10. It appears certain, however, that Smolts do not 

 always return during the same year as Grilse, but fre- 

 quently remain nine or ten months in the sea, returning 

 in the following spring as small-sized Salmon. 



[Note. It will thus be seen that the fry of the Salmon are called 

 Parrs until they put on their migratory dress, when they become 

 Smolts and go down to the salt water j Grilse if they return from 

 the sea during the first year of their migration ; and at all other 

 periods Salmon.~] 



11. It has also been clearly proved that, in general, 



