FLAT WORM ( PLAN ARIA ) 



327 



projecting through the full length of the pharyngeal chamber. It is 

 attached only at its proximal or anterior end and is perfectly free 

 otherwise. When it is extended or protruded through the mouth 

 opening which it fills, it forms a proboscis whose length may be as 

 great as, or greater than, that of the entire body. The trunks of the 



nc 



ex 



A. 



B. 



Fig. 117. — Structure of planaria. A, Digestive and excretory systems; B, nervous 

 system; 6r, cephalic ga iglia (btain) ; ex, excretory pore; int, intestine; l.ne, longi- 

 tudmal nerve; mo, mouth; o.ph, opening of pharynx; /j/i, pharynx. (From Parker 

 and Haswell, Textbook of Zoology, The Macmillan Company.) 



