PHYLUM PLATYHELMINTHES . 



237 



a short mouth-cavity into a cylindrical thick-walled chamber, the 

 pharynx (ph.), which is highly mobile, and is capable of being 

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



Fig, 182.— Flanaria. Digestive and excre- 

 tory systems, ej:. openings of excretory 

 system ; int. intestine ; vio. mouth ; 

 0. ph opening of pliarynx. (After Jijima 

 and Hatschek.) 



Flo. 1S3.— Planaria. Nervous system. 

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

 dinal nerve ; ph. pharynx. (After 

 Jijima and Hatschek.) 



may then be extended to a relatively considerable distance. 

 When retracted it lies within an enclosing mu.scular sheath. The 



