324 Fresh-water Mussels. 



ows till they seem to despair of catching an}' thing, 

 and will alight in the centre of a large pasture field 

 where there is no water, and stand there for hours 

 disconsolate. I suspect that the herons in winter 

 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 can scarcel}' find many ; 

 for though I have been over the water-meadows 

 da}^ after day for snipe, I seldom saw a frog about 

 them here. 



When the level of the mere, after a peculiarly dry 

 season, is ver}' low, is also a good time to observe 

 the habits of many other creatures. There are alwa3's 

 one or more crows about the neighborhood of the 

 lake ; but at such times a dozen or so may be seen 

 busily at work along the shore. They prey on the 

 mussels, of which there are great numbers in the lake. 

 An}- one passing b}' 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 

 e^'e, the mussel ma}' 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 

 travelled. One may occasionally be seen in the act 

 of movina: itself, and makino; the groove in the sand. 



