THE CRAYFISH. 



297 



lobster) is found in many of our rivers. It is of a dull- 

 greenish or brownish colour, pale-yellow on the under side, 

 with a little red on the limbs. The female has a much 

 broader tail than the male. It eats every imaginable 

 aquatic insect or animal, from the larvae of insects to the 

 water-rat. It also eats calcareous plants, as the stone- 

 worts, and even the weakly members of its own family are 

 devoured. For a detailed account of the natural history 

 of this crustacean see Professor Huxley's most interesting 

 volume, "The Crayfish." 



Owing to some unknown cause, the crayfish has entirely 



I. THE CRAYFISH. 



died out from the upper part of the river Kennet, and 

 consequently the trout have lost a most important food- 

 supply ; and it is possible that the redness of the flesh 

 for which the trout in this river were noted, and which 

 is not now so universal, was due in a great measure to 

 this crustacean, to the young of which, trout are extremely 

 partial. May not the cause arise from the absence in 

 the water of ingredients which were necessary for the 

 formation of the shell ? 



