216 



PLATYHELMINTHES. 



vasa deferentia through the penis, the oviduct (Od), the uterus 

 (Ut), and a muscular sac of unknown function (X}. 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 on each side 



FIG. 172. Diagrammatic representa- 

 tion of the anatomy of Planaria 

 Icwtea (after Leuckartand Nitsche). 

 D intestine ; Ph 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 piriform 

 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. 



w.a** 



FIG. 173. Anatomy of Leptoplana pallida (after 

 Quatrefages). G cerebral ganglion with the nerves 

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

 tine ; Od oviduct; V vagina; W. Goe female genera- 

 tive opening ; M. Goe male generative opening ; 

 T vas deferens ; Ov ova. 



