PHYLUM PLATYHELMINTHES 



259 



digenetic forms a single anterior and a single posterior sucker ; but 

 in some of the Digenetica the posterior sucker is wanting. Adhesive 

 papillae on the dorsal or ventral surface may supplement the 

 adhesive action of the suckers (Fig. 199, B.). In the Monogenetica 

 the suckers are often more numerous ; in the family Gyrodactylidce 



FIG. 201. Temnocephala minor, general view of the organisation, c. cirrus ; e. s. 

 ejaculatory sac ; ft. c. genital atrium ; i. intestine ; o. gerinarium ; oo. ootype ; ph. pharynx ; 

 pr. prostate glands ; r. d. strands of ducts of integumentary glands running forwards to the 

 tentacles ; r. g, groups of integumentary (rhabdite-forming) glands ; r.v. receptaculum ; 

 s. sucker ; t. testes ; te. tentacles ; t. s. terminal sacs of excretory system ; v. s. vesicula 

 seminalis. 



(Fig. 200, A) there is no anterior sucker, but at the posterior end 

 one or two discs armed with hooks; in the Polystomece (Fig. 200, 

 B) there is also a posterior disc on which are six suckers with 

 several hooks ; in the Temnocephalea (Fig. 201) there is no 

 anterior sucker, but the anterior end develops a row (two only in 

 Scutariella) of adhesive tentacles, while in Actinodactylella 



s 2 



