Chilton. — On Astacus fiuviatilis and Paranephrops setosus. 157 



branchia (pb) which has no lamella. The anterior arthrobranchia (ab) 

 (attached to the membrane uniting the base of the limb to the part of the 

 thorax to which it is articulated), also often comes away with the limb. 

 The basipodite (bp) and ischiopodite (ip) are both short and of nearly equal 

 length, the latter is broader than long. The meropodite (mp) is the 

 longest joint in the endopodite, it is about twice as long as broad. The 

 inner edge of these three last-mentioned joints is abundantly supplied with 

 setaa. The carpopodite (cp) is small and narrow. The protopodite (pp) is 

 subtriangular, expanding towards the distal end, the dactylopodite (dp) is 

 small and rounded. The last two joints are fringed with setae on both 

 sides. 



Third maxillipede (pi. XIX., fig. 8). — In this appendage the exopodite 

 (ex) is small compared with the rest of the limb, it reaches to nearly the 

 end of the ischiopodite of the endopodite. It is composed of two parts, 

 the undivided basal joint and the flagellum, the former being slightly 

 the longer. The coxopodite (cxp) bears the podobranchia (pb) and also the 

 corresponding anterior arthrobranchia (ab) ; at the base of the podobran- 

 chia is a small tuft of coxopoditic setaa (cxs) [see under Respiratory 

 Organs] . The basipodite (bp) is indistinctly divided from the ischiopodite 

 (ip) which is the longest joint of the endopodite. There are three or four 

 spines on its inner edge, and the outer edge is produced distally into a long 

 sharp spine. The meropodite (mp) is little more than half as long as the 

 ischiopodite, on its inner edge are three spines. The carpopodite (cp) is 

 narrow at its proximal end, but expands considerably at the distal end, the 

 inner corner of which bears a sharp spine. The propodite (jpp) is about as 

 long as the ischiopodite, it narrows towards the distal end ; the dactylopo- 

 dite (dp) is narrow, being about three times as long as broad. The inner 

 edges of the basipodite and succeeding joints are fringed with setas. 



The great claivs each bear a large podobranchia and a small tuft of coxo- 

 poditic seta?. The various joints of the limb are abundantly supplied with 

 strong spines arranged as follows : — The ischiopodite has two strong sharp 

 spines on the inside, and two short blunt ones on the outside ; the meropo- 

 dite has on the inside two rows containing six and four spines respectively, 

 and at the distal end a single spine placed between these two rows, on the 

 outside is a row of four spines, and there are one or two other spines at the 

 distal end ; the carpopodite has three large spines on the inside, one large 

 one on the outside, and smaller ones scattered over the joint ; on the under 

 side of the propodite there are two rows of three and four spines respectively 

 and one spine irregularly placed. On the side on which the movable finger 

 is there are five large spines in a row, and one large one more to the out- 

 side, on the other side are two rows extending right up on to the fixed 



