Till: TUHBKLLARIA. 



externally by a median pore on the oral face of the body, the 

 male aperture being posterior to the female. The margins of 

 the male aperture are produced into a curved prominence, the 



]HMl'lS. 



Those Tttrbellaria which resemble Macrostomum in having 

 a straight, simple digestive cavity, are termed Rkabdocvda. 

 Tlirv, f.n* the most part, possess ;i buccal proboscis, which is 

 capable of being protruded from, or retracted into a chamber 



FIG. 32.Oplstho)nutn (aftp.r Schulzc). a, central nervous gyetem ; ramification- of 

 the water-vessels are seen <!<><, t it : f>. mouth; c, proboscis; d. tester; . va* 

 deferent ia; /, vesicula seminalis ; g, penis ; A, sexual aperture : /. va-_ r iu:i ; A:, sper- 

 matheca ; /. ffermarium ; m, viteliariuoi ; w, uterus witli two ova iudosed within 

 their hard shells. 



formed by the walls of the circum-oral region of the body 

 32, c). 

 some (e. g., Prostomum) the anterior end of the body is 



(Fig. 32, c). 

 In 



