forming or not forming any branches, they may merge at the posterior end 



of the body, forming in this fashion a round or ellipsoidal figure (Dactylo- 



gyridae. Fig. 5). Very often when the ends of the intestinal trunks nnerge, 



a single smooth or branched extension stretches from the place of the 



junction posterior towards the attaching disc. The formation of lateral 



branches is observed both in forms 



with the trwo-trunked intestine as 



well as among the single-trunked, 



as for instance in Diplozoon para- 



doxum Nordmann(Fig. 231). We 



also note that the growths and 



branches of the intestinal trunks 



oriented inside the body can merge 



forming anastomoses between two 



trunks and givJng the intestines a 



OOImm] 



B.Imm 



Fig. 63. Gyrodactylus atherinae 

 Bychowsky, anterior end of the 

 body of an adult worm from the 

 gills of Atherina mochan pontica 

 caspia Eichw. near the Island of 

 Sara (Caspian Sea). Strongly 

 flattened (semi-diagrammatic). 



Fig. 64. Tetraonchus monenteron 

 (Wagener), adult worm from the 

 gills of Esox lucius L. from the 

 Delta of the Volga. Vitelline follicles 

 at the posterior end of the body are 

 somewhat rarified. 



strongly -branched form ( Polystoma , Fig. 22). Often the development of p 



these anastomoses is so powerful that the basic trunks become indistinguish- 

 able (for instance among certain Microcotylidae, Fig. 66). Basically, 

 smaller worms have a simpler form of intestine. The latter reaches the 

 greatest complexity among the larger marine forms. One must note that 

 complication of the intestine is observed independently in various syste- 

 matic groups and is correlated with an increase in the size of the animal. 

 Undoubtedly, a more equitable distribution of the food substances which are 



48 



42 



