here. Thus, one must recognize that Benedenia is characteristic for a 

 wide circle of Perciformes and Tetrodontiformes which are linked with 

 them and is encountered on Myliobatidae which are unrelated to them. 



Consequently, of the four genera of monogenetic trematodes 

 represented in Table 14, three--Choricotyle, Encotyllabe, and Benedenia, 

 are characteristic for Perciformes and one--Dactylogyrus, for Cyprini- 

 formes, although the last two genera are also encountered in single species 

 on families of fishes unrelated to their basic hosts. 



The last three genera parasitizing fishes-- Ancyrocephalus , 

 Gyrodactylus, and Microcotyle, are characterized by the occurrence on a 

 considerable number of families: in all three cases more than 15. 



Thus, the genus Ancyrocephalus , which consists at the present 

 time of 36 species is encountered on 23 families of fishes belonging to 7 

 orders, namely; Scopeliformes -- ? Scopelidae (1 species of Ancyrocephalus ); 

 Cypriniformes--Cyprinidae (10 species), Cobitidae (1 species); ? Ariidae 

 (2-1 species); Anguilliformes -- ? Muraenesocidae (1-0 species); Beloni- 

 formes--Belonidae (two species); Mugiliformes --Mugilidae (3-2 species); 

 Atherinidae (1 species); Perciformes --Serranidae (2 species); Priacanthidae 

 (1 species); Percidae (1 species); Lutianidae (1 species); Liognathidae 

 (1 species); Lethrinidae (1 species); Ephippidae (1 species); Drepanidae 

 (2 species); Cichlidae (1 species); Acanthuridae (2-1 species); Gobiidae 

 (1-0 species); Eleotridae (2-1 species); Platycephalidae (4 species); 

 Tetrodontifornnes--Balistidae (1 species); Ostracidae (1 species). Just 

 as Cleidodiscus and Urocleidus, this genus is artificial in its contemporary 

 scope, but just as both above-mentioned ones, it occurs basically on the 

 Perciformes. For the time being it is excluded from the detailed discussion. 



In the genus Gyrodactylus, from the total volume of the species 

 described about 60 (actually there are many more) are authentically known 

 from 18 families related to 10 orders , namely: Chimaeriformes-- 

 Callorhynchidae (1 species of Gyrodactylus ); Clupeiformes--Salmionidae 

 (2 species); Esocidae (1 species); Cypriniformes --Ameiuridae (1 species); 

 Catostomidae (1 species); Cyprinidae (14-15 species); Cobitidae (15-13 

 species); Gasterosteiformes --Gasterosteidae (3 species); Gadiformes-- 

 Gadidae (8 species and subspecies); Cyprinodontiformes --Cyprinodontidae 

 (2 species); Mugiliformes --Atherinidae (1 species); Ophiocephaliformes -- 

 Ophiocephalidae (1 species); Perciformes --Sciaenidae (1 species); Agonidae 

 (1 species); Zoarcidae (1 species); Cottidae (2 species); Blenniidae (1 species); 

 Cyclopteridae (1 species); Comephoridae (1 species); Cottocomephoridae 

 (2 species); Pleuronectiformes --Pleuronectidae (2 species). Thus, one can 

 say about this genus that it is distributed on the most varied fannilies of fishes, 

 some linked consanguinously with each other, and others not at all. One must 

 remennber also that undetermined, as far as the species is concerned, 

 representatives of the genera were often encovmtered on various Amphibia, p. 265 

 mainly on tadpoles of the genus Rana (Sproston, 1946, and others). 



300 



