18/8.] AND DISTKIBUTION OF THE CRAYFISHES. 



765 



Fig. 5. 



Astacopsis franklinii. 



The outer face of the podobranchia of the antepenultimate thoracic limb of 

 the left side ( X 3^). II. The inner face of the same podobranchia : br, 

 branchial filaments; I, rudimentary lamina. II a. The apex of the same, 

 more highly magnified. III. A transverse section of the podobranchia at 

 about the junction of its middle and upper thirds. TV. The extremity of 

 one of the hooked filaments ; and V, that of one of the hooked setae. In 

 these two figures the vertical line represents yfjj of an inch magnified to 

 the same extent. VI. The eoxopoditic setae ( X3j). 



