FlG. 13. — Astacus JluviatilU. — The alimentary canal and livers seen from 

 above (nat. size), id, bile-duct ; cce, cascum ; cs, cardiac portion of 

 stomach, the line pointing to the cardiac ossicle ; hg, hind-gut ; mg, 

 mid-gut ; pe, pterocardiac ossicle ; ps, pyloric portion of stomach, 

 the line pointing to the pyloric ossicle ; r, ridge separating mid-gut 

 from hind-gut ; zo, zygocardiac ossicle. 



