HOMARUS AND NEPHROPS. 



259 



fully developed pleurobranchiae. Moreover, the bran- 

 chial filaments of these gills are much stiffer and more 

 closely set than in most crayfishes. But the most im- 

 portant distinction is presented by the podobranchise, in 

 which the stem is, as it were, completely split into two 

 parts longitudinally (as in fig. 68, B) ; one half {ej)) 



C' st 



Fig. 68. 'Pod.dbxB.nchidd oi K, Parastacm ; B, JVephj'ops ; C,Palcemon. 

 A', C, transverse .qections of A and C respectively, a, point of attach- 

 ment ; al, wing-like expansion of the stem ; b, base ; hr, branchial 

 filaments ; ep, epipodite ; I, branchial laminae ; jd, plume ; st, stem. 



corresponding with the lamina of the crayfish gill, and the 

 other {pV) with its plume. Hence the base (6) of the 

 podobranchia bears the gill in front; Avhile, behind, it 

 is continued into a broad epipoditic plate {ep) slightly 

 folded upon itself longitudinally but not plaited, as in the 

 crayfish. 



The Norway Lobster {Nephrops norvegicus, fig. 69) 



