PHYSIOLOGY OF THE INVERTEBRATA. 59 



" Tsile-duct," which opens into the anterior portion of the 

 intestine. 

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





^ ha 





h II 



of the Cnistacea. To this order belong the lobster (Homarus), 

 crayiish (Astaciis), and shrimp (Palcevion). 



The alimentary canal is well defined, especially the stomach. 



