There are two pairs of eyes in front of the buccal opening on the dorsal 

 surface of the body. They are in the form of cup-shaped masses of pig- 

 ment, in a cavity of which 

 lie spherical hyaline lenses. 

 The lenses of the posterior 

 pair of eyes are approxi- 

 mately 0.016 mm in di- 

 ameter and lie in front of 

 and to the side of the pig- 



Fig. 196. Benedenia derzhavini (Lajman), adult 

 worm from the interior surface of the operculum 

 of Sebastodes schlegeli (Hilg. ) near Vladivostok 

 (Sea of Japan) 



Fig. 197. Benedenia 

 melleni (MacCallum), 

 free -swimming larva. 

 Natural size 0. 23 mm. 

 (According to Jahn and 

 Kuhn, 1932). 



mented cups. The lenses of the first pair are 0. 012 mm in diameter and 

 lie posteriorly and to the side. The head suckers, which are not fully 

 developed, have the shape of padded sections easily visible in live indi- 

 viduals. The excretory system (Fig. 199) is represented by two relatively 

 large excretory bladders located somewhat behind and laterally to the 

 buccal opening, with 4 canals leading from them, and 10 pairs of flame 

 cells. The excretory system opens in dorsal pairs just as among adult 

 forms. There are 2 large excretory canals each starting from the 



1 



One must suppose that the description of the authors regarding the 

 number of lateral canals is not accurate because the presence of two 

 basic canals on each side is characteristic for the majority of mono- 

 genetic trematodes in which the excretory systenn has been studied. 



192 



