lai 



ZOOLOGY 



to Faxon, two genera — As'tacus and Cam'barus — of which the 

 latter can be subdivided into the suljgenera Cambarus and 

 Cambaroides. These groups occupy distinct geographical 

 areas. The genus Astacus is found, in the t)ld World, in 

 Europe and western Asia as far south as the Aral and Caspian 

 seas, and in America in the region west of the Rocky Moun- 



FiG. 130. — The distribution of crayfishpR. Tlio sliadcrl areas are inhabited 

 by various genera as described in the text. 



tains, draining into the Great Salt Lake and the Pacific Ocean. 

 It is thus seen to occupy the western sides of the two northern 

 continents. Likewise Cambarus and Cambaroides occupy the 

 two eastern coasts of the northern continents; for Camba- 

 rus is found in North America east of the Rockj- Mountains 

 in the region boimded on the north by Lake Winnipeg and 

 New Brunswick and (in the south liy Guatemala and Cuba, 

 while Cambaroides is limited to the Amoor River liasin in 

 Asiti, and to Japan. 



We thus find among the craj'fishes what is known as dis- 



