ON TEOUT. 



61 



* Denotes that mature fish occurred in that particular year-class. 



Here we see in the first place that the proportion between males and 

 females varies greatly in different localities. 



In Aagvand and M01nbugtselv we find the typical decrease in the age 

 of females mentioned in the case of Utskarpen. 



In the Os river the samples have been taken from a succession of 

 catches from the mouth of the river and up stream, and numbered 

 respectively 1, 2, and 3. Here, again, nearest the mouth, we find the 

 typical absence of older females, whereas the higher up the river we go 

 the more numerous do they appear to be. 



The proportion between the sexes is reversed, however, in Kvernvand. 

 Here there are peculiar conditions owing to the out-flow being a very 

 small burn, which is dry for a great part of the year, and the fish conse- 

 quently are only able to ascend and descend when there is a spate, and I 

 am compelled to state in this instance that I can only accept with considerable 

 reserve the proportional number of individuals of the two sexes in the sample, 

 as the writing of my amateur assistant at the examination has proved liable 

 to misinterpretation. 



The next point to notice, from the figures marked with *, is that 

 mature individuals may occur as early as the third, or sometimes even 

 the second year, and that maturity is not confined to males, mature females 

 also occurring.* 



A third point is that the maximum age for fish in these streams only 

 rarely exceeds the maximum age at which sea trout migrate, and the 

 numbers of individuals in the year-classes decrease, too, at a more or less 

 rapid rate, as we approach this maximum age. There is thus nothing in 

 this connection to prevent us assuming that this decrease is connected with 

 migration. That it is due to migration, so far as a large part of the stock 



* In the case of the Os river my investigations took place so early in the year that 

 it was only in a few instances we could decide with any degree of certainty whether 

 maturity had commenced. 



