The digestive systems, similar as a whole, differ in the fact 

 that among Dionchidae the trunks of the intestine merge at the posterior 

 end, but not in Monocotylidae. Further, as is obvious from the diagnosis, 

 not less distinct are the differences of the structure of the sex system; 

 they pertain to the peculiarities of the ovary, of the testes, and of the 

 efferent ducts. Particularly substantial are the peculiarities of the location 

 of the ovary--in Dionchidae it is flask-shaped and does not embrace one 

 of the branches of the intestine, which is especially characteristic for 

 Monocotylidae. Thus, one can consider the separation of Dionchidae from 

 Monocotylidae as quite legitimate. As indirect substantiation of this is the 

 parasitizing of bony fishes by the first and of Elasmobranchii by the second. 



If we compare Dionchidae with Capsalidae we see a number of 

 important similarities which show that there are close consanguinous ties 

 between these tw^o families w^hich are more important than among both of 

 these families with Monocotylidae. Thus, the presence of one pair of edge 

 hooks in the posterior part of the disc, the common sex aperture at the 

 s ide of the body, and the absence of armature of the male sex organ are 

 characteristic for all Capsalidae just as for Dionchidae. At the same 

 time the merging of the intestinal trunks at the posterior end of the body 

 is peculiar for a number of Capsalidae. All these characteristics are 

 sufficiently serious to consider that both families are very close to each 

 other. 



4. Family Capsalidae Baird, 1853 



Tristomidae Cobbold, 1877; Tristomatidae Gamble, 1896; 

 Encotyllabidae Monticelli, 1888, 



Monopisthocotylinea, having middle and large sizes in the adult 

 state. The attaching apparatus consists of a sucker-shaped disc divided 

 by muscular septa into a number of peripheral and one central depression 

 and of chitinous armature. In certain cases the septa can be weakly 

 expressed or completely absent. The armature of the disc consists of 14 

 edge hooks and 2-6 middle hooks which can be absent secondarily. In 

 contrast to Monocotylidae and Loimoidae it is characteristic that only 2 

 edge hooks lie along the edge of the disc between the 2 posteriormost septa 

 in which the middle hooks are located, and the remaining 12 are located in 

 front of the above-mentioned septa. The anterior end of the body has two 

 cephalic adhesive formations having the appearance of glandular fields or 

 more or less well-developed suckers. Between these formations there is 

 a variously expressed head or cephalic lobe. There are 4 eyes. The 

 intestine has numerous external and internal branching outgrowths, 

 as an exception it is simple without any outgrowths. Usually the intestinal 

 trunks terminate blindly, less often they nnerge with each other. The 

 male sex aperture and the aperture of the uterus open on the side of the 



445 



