4.— 



3 

 \ 



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/5. 



U. 



Jr. 



3- 



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Flo. 59.— ^stocws fiuviatilu.—VejitTal (A, B, C, P) and lateral (D, E) views of the 

 embryo in succitssive stages of development (after Rathke, x 15). A is a little more 

 advanced than the embryo represented in fig. 58, F : D, E, and P are views of 

 the young crayfish when nearly ready to be hatched : in E, the carapace is 

 removed, and the limbs and abdomen are spread out. 1—14, the cephalic and 

 thoracic appendages ; ab, abdomen ; hr, branchiae ; c, carapace ; ep, epipodite 

 oFtl'p first niaxillipede; gg, green gland; h, heart; Ih. labrum ; Ir, liver; m, 

 mandibular muscles. 



