PHYLUM PLATYHELMINTHES 



243 



In the Monogenetica the suckers are often more numerous ; in the 

 family Gyrodactylidce (Fig. 189, A) there is no anterior sucker, but 



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ertt 



v.d. 



en, 



i/it 



FIG. 189. Monogenetic Trematodes. 'A. fl>n-nilu?tiilu*. <-il. disc bearing hooks and pi o- 

 cesses at the posterior end ; c/if. intestine ; <j1. unicellular glands whose ducts open on the 

 surface about the anterior end ; mo. mouth ; oo&p. oosperm ; or. ovary ; p. penis ; ph. pharynx ; 

 in. testes. B, PoK/stomum. <n. intestine ; rt. p. genital pore ; 7x0. mouth ; pl>. pharynx ; or 

 ovary; te. testes ; u. uterus ; >-., r. <7. vas deferens ; vit. vitelline glands ; cit. ,/. vitelline ducts ; 

 .';. sperm-duct probably directly connecting the testes with the oviduct. (From 51. Braun.) 



at the posterior end one or two discs armed with hooks : in the 

 Polystomece (Fig. 189, B) there is also a posterior disc on which are 



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