CHAPTER XV 



THE CRAYFISH. ARTHROPODA 



Crayfishes are found in many English rivers, especially in 



those which rise in chalk or limestone hills. 



They are little, lobster-like creatures, which 

 make burrows in the river banks. They dislike strong 

 light and during the daytime generally remain in their holes 

 with only their pincers and long feelers projecting. When 

 they come out they crawl stealthily about, searching con- 

 stantly for their food, which consists of organic matter 

 of any kind, plant or animal, dead or alive, that they 

 are able to seize and break up with their pincers. If 

 danger threatens, they dart backward suddenly and swiftly. 

 They are used for food, especially for garnishing salads, 

 and were formerly caught in large numbers in this country 

 by means of wicker crayfish-pots, but in 1887 their numbers 

 were greatly reduced by a disease, and at present crayfishes 

 for the table are imported from the Continent. 



The English crayfish, Astacus torrentium, is about three 



inches long, and of a dull, greenish colour, 

 Features. which harmonises well with the surroundings 



in which it lives. The species imported from 

 the Continent is A. fluviatilis, which is larger and has red 

 colouring on the pincers and legs. The body of a crayfish 

 is covered with a cuticle thickened and strengthened by salts 

 of lime to form an armour : it is segmented, each segment 

 bearing a pair of jointed limbs, but in the front part the 

 segments are fused to form a fore-body or cephalothorax, 

 where the only conspicuous sign of their existence is the 

 presence of several pairs of limbs, though careful examina- 

 tion shows that parts of the armour and certain internal 



organs are also segmentally arranged. The rest of the 



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