re : abs arbo plbiz  arbis plbis 
t Se Se i ae 
\‘— 
Fic. 4.—Astacus fluviatilis.—In A, the gills, exposed by the removal of the branchio- 
stegite, are seen in their natural position ; in B, the podobranchiz (see p. 75) are re- 
moved, and the anterior set of arthrobranchie turned downwards (x 2): 1, eye-stalk ; 
2, antennule ; 3, antenna; 4, mandible ; 6, scaphognathite ; 7, first maxillipede, in B 
the epipodite, to which the line points, is partly removed ; 8, second maxillipede ; 
9, third maxillipede ; 10, forceps ; 14, fourth ambulatory leg ; 15, first abdominal 
appendage ; xv., first, and xv1., second abdominal somite; arb. 8, arb. 9, arb. 13, 
the posterior arthrobranchiz of the second and third maxillipedes and of the third 
ambulatory leg ; arb’. 9, arb’. 13, the anterior arthrobranchiz of the third maxillipede 
and of the third ambulatory leg ; pbd. 8, podobranchix of the second maxillipede ; 
pod. 13, that of the third ambulatory leg; plb. 12, plb. 13, the two rudimentary 
pleurobranchiz ; plb. 14, the tunctional pleurobranchia ; 7, rostrum. 
