LIMNyEA PEREGRA. 153 



of their dead brethren. Clessin observes that it attacks the 

 shells of its fellows only if vegetable food is wanting. 



Mr. Jones states that he had frequently given L. stagnalis and 

 Z. limosa (another name for Z. peregrd) dead bleak and other 

 small fish, which they have reduced to a skeleton in a very short 

 time, although abundance of vegetable food was at hand. Dr. 

 Gray says that in the spring these animals are often infested with 

 a small, slender species of Gordius, which afifix themselves to the 

 edge of the mantle over the back of the neck. These parasitic 

 worms are so common that Draparnaud mistook them for the 

 respiratory organs of the animal. They are also preyed upon by 

 leeches and fishes as well as aquatic birds. In fact, ducks are so 

 particularly fond of molluscs, that where they are kept it is almost 

 useless to search for shells. 



Mr. J. W. Williams records having kept a number of Dytisci 

 which he fed upon Z. stagnalis and Z. peregra. The beetles, 

 though eating both species, evidently showed a preference for 

 Z. stagnalis. 



Though a hardy species, Z. peregra hibernates for a short time 

 during winter, but for a rather longer period than Z. stagnalis. The 

 Rev. W. C. Hey records its behaviour under somewhat peculiar cir- 

 cumstances. The Ouse at York was considerably lowered by 

 opening Naburn Lock, exposing a number of fresh-water shells on 

 the muddy banks. The same night a keen frost set in, the mud 

 becoming perfectly hard to the water's edge. The Z. peregra., 

 however, burrowed itself a hole in the mud, apparently by a rota- 

 tory movement of the shell, and lay there warm and damp. He 

 says : — " I opened several of these holes, and do not think a 

 single specimen died." 



That it burrows in the mud to escape the cold I readily admit. 

 At the same time, it does not seem to possess the knowledge how 

 to escape the effects of heat as successfully as Mr. Hey credits it 

 with regard to the frost, for we often find hundreds dead at the 

 bottom of dried-up ponds in summer. But some allowance 

 should be made here, for they may perhaps have deposited their 

 ova and so completed their life purpose. But so long as there is 

 sufficient moisture it can survive a very high temperature. In 

 some of the mill-cisterns at Cheadle, Staffordshire, into which the 



