Mussels in the Lake 297 



time that come to the ponds do so for the fish which lie 

 at the bottom on the mud packed close together, that 

 is, when the water is not deep. It is said that when ice 

 protects the fish herons eat the frogs in the water-meadows ; 

 but they can scarcely find many, for though I have been 

 over the water-meadows day after day for snipe, I seldom 

 saw a frog about them here. 



When the level of the mere, after a peculiarly dry 

 season, is very low, is also a good time to observe the 

 habits of many other creatures. There are always one or 

 more crows about the neighbourhood of the lake ; but at 

 such times a dozen or so may be seen busily at work along 

 1 he shore. They prey on the mussels, of which there are 

 great numbers in the lake. Any one passing by the water 

 when it is so shallow can hardly fail to notice long narrow 

 grooves in the sand of the bottom. These grooves begin 

 near the edge — perhaps within a foot of it — and then run 

 out into the deeper part. By following these with the 

 eye, the mussel may often be seen in a foot or two of 

 water — sometimes open, but more generally closed. The 

 groove in the sand is caused by the keel of the shell as the 

 creature moves. 



There are hundreds of these tracks; the majority 

 appear to run from shallow to deep water, but there are 

 others crossing and showing where the mussel has tra- 

 velled. One may occasionally be seen in the act of moving 

 itself, and making the groove in the sand. But they seem 

 as a rule to move most at night, and to approach the shore 

 closest in the darkness. In the deep water they are safe ; 

 but near the edge the crows pounce on them and may be 

 seen peering about almost all day long. 



Besides those that are eaten on the shore^ numbers of 

 mussels are carried up on the rising ground where the 



