CHAPTER VII 



THE CRAYFISH AND ITS ALLIES 



THE crayfish belongs to the class of Crustacea, since it 

 breathes by means of gills, possesses two pairs of antennae, 

 a pair of mandibles bearing palps, and a pair of append- 

 ages on all body segments excepting the last. The 

 Crustacea are divided into two subclasses,- - Entomostraca, 

 of which Daphnia is an example, and Malacostraca, to 

 which the crayfish belongs. All the Malacostraca 1 have 

 19 pairs of appendages. 2 



The crayfish, 3 which is closely related to the marine 

 lobster, 4 is an inhabitant of fresh-water lakes, rivers, and 

 pools. It thrives in diverse surroundings; for some species 

 prefer cool mountain streams and others muddy pools, 

 while certain species, both in Europe and America, are 

 found in brackish as well as fresh water. Indeed, the 

 European Astacus fluviatilus is said to be frequently 



s, soft ; 'ocrrpaKov, shell (since the shell is less hard than that 

 of mollusks). 



2 Keys to the six chief orders of Malacostraca and to families of the 

 stalk-eyed Crustacea will be found in the Appendix to this Chapter, p. 122. 



3 The old English spelling of this word was ''crevis'' or "crevice." 

 The ere came to be spelled phonetically cm//, while vis became 

 changed to fisli in accordance with the popular nomenclature of all 

 aquatic animals. 



4 The English word " lobster " is from the old English lopystre, which is 

 probably corrupted from the Latin locusta, by which term Pliny refers to 

 the lobster. 



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