PHYSIOLOGY OF THE INVERTEBRATA. 59 



'' bile-duct. '" wliicli opens into the anterior portion of the 

 intestine. 

 (33) The Macroura form the last order we have to consider 





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of the Crustacea. To this order belong the lobster {Homarvs), 

 crayfish (Astaci's), and shrimp (Paknnon). 



The alimentary canal is well defined, especially the stomach. 



