154 LECTURE XII. 



what is called the river-louse, or rather leech, 

 which fixes itself on the inside of the gills, and 

 drives the salmon back to the sea. On arriving 

 there, it has been ascertained that these leeches 

 do not live an hour, and the growth of the fish 

 is then wonderfully rapid, increasing in weight, 

 as has been found by marking fish on their way 

 to the sea, to five or six pounds before the next 

 ascent of them in the rivers, the following year. 

 It is evident, then, that the creatures I have 

 mentioned serve to propel the salmon to and 

 from rivers: thus fulfilling those instincts which 

 Almighty God has implanted in them. 



I do not suppose that many of you have seen 

 the kingfisher in its wild state, as they are 

 almost exclusively river birds, although, during 

 hard frosts, they may possibly frequent the sea- 

 shore in search of food. Their nests are made 

 very often in old rat-holes in the banks of rivers, 

 and generally to a depth of three or four feet. 

 Now, as the kingfisher's food consists of small 

 fish, and it is a pretty sight to see them, with 

 their brilliant colours, dart into the water, and 

 as they throw out the fish-bones after they have 

 sucked out the juices, they make, with these 

 bones, a curious and interesting nest. The 



