PHYLUM PLATYHELMINTHES 



243 



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

 family G-yrodactylidce (Fig. 189, A) there is no anterior sucker, but 



FIG. 189. Monogenetic Trematodes. A, G>rro<'act >//!'.. cil. disc bearing hooks and pro- 

 cesses at the posterior end ; eat. intestine ; gl. unicellular glands whose ducts open on the 

 surface about the anterior end ; mo. mouth ; oosp. oosperm ; ov. ovary ; j>, penis ; pit. pharynx ; 

 te. testes. B, Polystojjutm. en. intestine ; y. p. genital pore ; mo. mouth ; ph. pharynx ; or 

 ovary ; te. testes ; u. uterus ; r., v. d. vas deferens ; fit. vitelline glands ; -fit. </. vitelline ducts ; 

 x. sperm-duct probably directly connecting the testes with the. oviduct. (From M. 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 



R 2 



