Ps 
‘ 
Fig. 17.—Astacus fluviatilis.—A, one of the podobranchie from the 
outer side ; B, the same from the inner side ; C, one of the arthro- 
branchiz ; D, a part of one of the coxopoditic sete ; E, extremity of 
the same seta; F, extremity of a seta from the base of the podo- 
branchia ; G, hooked seta of the lamina; (A—C, x 3; D—G, highly 
magnified). 0, base of podobranchia; cs, coxopoditic sete; cap, 
coxopodite ; 7, lamina, pl, plume, and st, stem of podobranchia ; 
t, tubercle on the coxopodite, to which the seta are attached. 
