Fig. 2. — Astacns JfiiriatUis. — Dorsal or tergal views (nat. size^. A, male; 

 B, female : — bcf/, branchio-cardiac groove, which marks the boun- 

 dary between the pericardial and the branchial cavities ; <?//, cervical 

 groove ; these letters are placed on the carapace ; r, rostrum ; f, t\ 

 the two divisions of the telson ; i, eye-stalks ; 2, antennules ; S, 

 antennae ; 20, lateral lobes of tail-fin ; xv-xx, somites of the 

 abdomen. 



