234 



ZOOLOGY 



SECT, 



thrust out as a proboscis through the mouth, beyond which it 

 may then be extended to a relatively considerable distance. 

 When retracted it lies within an enclosing muscular sheath. The 



FIG. 185. Planaria. Digestive and ex- 

 cretory systems, ex. openings of excre- 

 tory system ; int. intestine ; mo. mouth ; 

 o.ph. opening of pharynx. (After Jijima 

 and Hatschek.) 



FIQ. 186. Flanaria. Nervous system. 

 br, brain ; eye, eye ; I. ne. longitu- 

 dinal nerve ; ph. pharynx. (After 

 Jijima and Hatschek.) 



cavity of the pharynx opens in front into the intestine (int.), which 

 almost immediately divides into three narrow main branches, one 

 running forward in the middle line, the other two running back- 



