pdb.Q 



7H/6.I3 



15 



14 



8 10 



r7>.8 (17*6.9 pn>.!2 arb. 13 pit 13 



" ' y ' -" 



FIG. 4. Astacus ftuvifttilis. In A, the gills, exposed by tlie removal of the branchio- 

 stegite, are seen in their natural position ; in B, the, podobranchiee (see p. 75) are re- 

 moved, and the anterior set of arthrobranehise turned downwards (x 2) : 1, eye-stalk ; 

 2, antennule ; 3, antenna ; It, mandible ; 6, scaphognathite ; 7, iirst maxillipede, in B 

 the epipodite, to which the line points, is partly removed ; 8, second maxillipede : 

 9, third maxillipede ; 10, forceps ; Ik, fourth ambulatory leg ; 15, first abdominal 

 appendage; xv., first, and xvi., second abdominal somite; arJ>. 8, arb. 9, arb. 13, 

 the posterior arthrobranchia? of the second and third maxillipedes and of the third 

 ambulatory leg ; arb'. U, arb'. 13, the anterior arthrobranchise of the third maxiiliptde 

 and of the third ambulatory leg ; pbd. S, ]iodol)ranchia' of the second maxillijiede ; 

 pbd. 13, that of the third ambulatory leg ; )>1b. 1~', i>lb. 1J, the two rudimentary 

 pleurobranchia! ; plb. lit, the functional pleurobranchia ; r, rostrum. 



