- 8 



12 



13 



Pig. 256. — Dissection o( /fololhuna tuitolosa. x ^. 1, Feelers ; 2, feeler-ampullae ; 3, 

 ring-canal ; 4, Polian vesicle ; 5, stone-canals ; 6, radial canal ; 7, one of a pair of 

 longitudinal muscles ; 8, genital tubes ; 9, intestine ; 10, radiating muscles of 

 cloaca ; 11, base of respiratory tree ; 12, ventral blood-vessel ; 13, plexus of dorsal 

 Wood-vessel. (After Ludwig.) 



