piJ b.8 



J)<lb.\i 



arlt.Q (iri.f> j>lh.\2 <irh.V3 p{6.l3 





am 



I'T 



ain 



arb'.\3 



Fig. 4. — Astn<nis fluviotilis. — In A, the gills, exposed by the removal of the branch! o- 

 stegite, are seen in their natnral jiosition : in B, the poclobranchiie {see 'p. 75) are re- 

 moved, and theaiiterior set of artlirolirancliiie turned dinvnwards(x 2) : i, eye-stalk ; 

 S, antenniile ; S, antenna : i, mandible : 6', scaphognathite : 7, tirst niaxillipede, in B 

 the epijiodite. to which the line points, is jiartly removed : S, second niaxillipede ; 

 9, third niaxillipede ; 10, forceps ; 1/,, fourth ambulatory leg ; 15, first abdominal 

 appendage; xv., first, and xvi., second alidomiiial somite; arh. S, arb. 9, orb. I,>, 

 the posterior arthrobrnnchiie of the second and third iiiaxi!li]iedes and of the third 

 ambulatory leg ; cirb'. 9, arh'. IS, the anteriorarthrobranchia' of the third maxiiliiiede 

 and of the third ambulatory leg ; }ibd. 8, iiodobranchia' of the second niaxillipede ; 

 pbd. 13, that of the third ambulatory leg: plb. 12, plb. 13, the two rudinnntary 

 pleurobrauchiaj ; plb. Ih, the funetii>nal pleurobranchia ; r, rostrum. 



1 



