196 SALMONIA. 



small scales, which, placed like those of 

 serpents, must facilitate their progressive 

 motion: these scales have been microsco- 

 pically observed by Lewenhoeck. (Phil. 

 Trans, vol. iv.) Eels migrate from the salt 

 water of different sizes, but I believe never 

 when they are above a foot long and the 

 great mass of them are only from two and 

 a half to four inches. They feed, grow, and 

 fatten in fresh water. In small rivers they 

 seldom become very large ; but in large 

 deep lakes they become as thick as a man's 

 arm, or even leg ; and all those of a consi- 

 derable size attempt to return to the sea 

 in October or November, probably when 

 they experience the cold of the first autumnal 

 rains. Those that are not of the largest 

 size, as I said before, pass the winter in the 

 deepest parts of the mud of rivers and 

 lakes, and do not seem to eat much, and 

 remain, I believe, almost torpid. Their 

 increase is not certainly known in any given 

 time, but must depend upon the quantity of 

 their food : but it is probable they do not 

 become of the largest size, from the small- 



