PHYLUM ARTHROPODA 



501 



plate (ep) having a plume-like gill (g) attached to it. Obviously, 

 such an appendage is biramous, but with one of its branches 

 greatly in excess of the other : the first two segments of the axis 

 (pr. 1 form the protopodite, its remaining five segments 



(en. 1-6) the endopodite, and the feeler, which is directed out- 

 wards, or away from the median plane, the exopodite (ex). The 

 folded plate (ep) is called the epipodite : in the natural position 



en.3 



5. 2". d Maxilla 6. I* Maxilliped 



e.Cobulafory Organs lO.Swimming Feot 



11. Uropod 



of Astacus. 



vs of protopodita ; 

 tley.j 



of the parts it is directed upwards, and lies in the gill -cavity 

 between the proper wall of the thorax and the gill-cover (Fig. 404). 

 Its position is thus very similar to that of the flabelluni of Apus, 

 while the gill attached to it is comparable to the bract. 



The five legs (S) differ from the third maxillipecl in their gr. 

 size, and in having no exopodiic : in the fifth or last the epipo- 

 also is abs-nu The first three of them have undergone a cur 



