THE BIOLOGY OF THE CKAYFISH 



F. E. CHIDESTER 



Rutgers College 



Introduction 



The first reference to the crayfish in scientific litera- 

 ture is in Aristotle's "History of Animals," where he 

 speaks of the "small Astaci which breed in the rivers." 



Aristotle and the older naturalists used the term Astaci 

 to include both the crayfish and the lobster. 



Faxon divides the crayfish into two great groups (24) : 

 One, restricted to the northern hemisphere, is found 

 in Europe, Asia and North America. The other is found 

 in the southern hemisphere, in Australia, Tasmania, New 

 Zealand, Fiji Islands, Madagascar and South America. 



The islands now inhabited by crayfish, such as Eng- 

 land, Japan and Cuba, were probably once connected 

 with the mainland. 



In speaking of the distribution of the crayfishes, Faxon 

 says : 



The northern family of crayfishes contains two genera, Astacus and 

 Cambarus. These groups occupy distinct geographical areas. The 

 genus Astacus is found in the old world in Europe and western Asia 

 as far as the Aral and Caspian Seas, and in America in the region west 

 of the Rockv Mountains, drainiiur into the Great Salt Lake and the 

 Pacific Ocean. It is thus seen to occupy the western sides of the two 



Rocky Mountain^ in th" n 2 ^ncTis hounded ^J ^ 01 ^ b ? Lak * 



It is comparatively easy to distinguish the common 

 Cambarus from the Astacus of Europe and western 

 America. Members of the genus Astacus have eighteen 



