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

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

 dary between the pericardial and the branchial cavities ; eg, cervical 

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

 the two divisions of the telson ; i, eye-stalks ; 2, antennules ; 3, 

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

 abdomen. 



