216 



PLATYHELMIXTHES. 



vasa cleferentia through the penis, the oviduct (0<7), the uterus 

 (Ut), and a muscular sac of unknown function (A'). There are 

 two ovaries (Ov) placed between the third and fourth pairs of 



intestinal caeca or thereabouts. The two 

 oviducts (Od) pass backwards, receiving 

 as they go the yolk -glands which are 

 placed between the caeca of the intes- 

 tine ; they join to open by a single tube 

 into the genital atrium. The testes are 

 numerous vesicles placed irregularly be- 

 tween the gut caeca, and communicating 

 with a longitudinal tube 011 each side 



FIG. 172. Diagrammatic representa- 

 tion of the anatomy of Planaria 

 lactea (after Leuckart and Nitsche). 

 I) intestine ; Pli pharynx ; M open- 

 ing of sheath of pharynx ; E exter- 

 nal openings of excretory vessels ; 

 To tactile organs ; Gl cerebral gan- 

 glion ; Ln origin of lateral nerve ; 

 Ov ovary : Od oviduct (anterior 

 and posterior part only shown) ; 

 Ut uterus ; X muscular piriforin 

 organ ; Go external genital opening ; 

 Vd vesiculae seminales opening 

 into the base of the penis. The 

 yolk-gland and testes are omitted, 

 and the vasa deferentia are not 

 shown. 



Flo. 173. Anatomy of Leptfiplana pallida (after 

 Quatrefages). G cerebral ganglion with the nerves 

 given off from it : mouth ; D branches of intes- 

 tine ; Od oviduct; V vagina; 1C. Goc female genera- 

 tive opening ; M. Goe male generative opening ; 

 T vas deferens ; Ov ova. 



