vi CONTENTS. 



Page 



Table showing the Geographical Disteiuution of every Species of Camua- 



eus and astacus 157 



Table showing our Present Knowledge of the Distribution of the North 

 American Species of Cambarus and Astacus, arranged according to 

 States and Territories 1C5 



Distribution of the North American Species of Cambarus and Astacus 



according to River Systems 173 



General Conclusions derived from the Facts known concerning the Geo- 

 graphical Distribution of the Astacid^ 175 



Index to the Species - . . . 181 



Explanation of the Plates , ... 183 



