ARENICOLA. 



213 



Food canal. (i) The buccal cavity is protrusible as a 

 proboscis " or introvert, which grips the sand, and bears 



FIG. 102. Dissection of lob-worm from dorsal surface. 



J/., Opening of retracted buccal cavity: /., gullet;.^/., di%'erticula 

 on first diaphragm ;-/"., oesophageal glands; d., dorsal blood 

 vessels ; ef'., first efferent branchial ; g., stomach intestine ; 6 ., 

 sixth nephridium ; e/ iS . , thirteenth efferent branchial ; a/^ 3 . , 

 thirteenth afferent branchial; ., anus; / ] ., first afferent 

 branchial ; //., heart of left side. 



