and others), and the latter genetically, "are undoubtedly linked with the 

 lowest Percoidei and particularly perhaps originate from Carangidae. " 

 (Nikolski, 1954). Gregory on the other hand simply includes Carangidae 

 in the group of Scombroidei (Gregory, 1951). 



Finally, Microcotyle pomacanthi is listed by MacCallum as 

 being encountered on three species of Chaetodontidae and one species of 

 Sparidae, Serranidae, Pomadasiidae, and Labridae. All these families 

 are related to the Perciformes although the degree of their consanguinous 

 relations is very different. Thus, the first four families are related to 

 the superfamily Percoidae. And the last family, Labridae, is related to 

 the same suborder, Percoidei, but to a special superfamily Labroidae, 

 i.e. , it is rather more distant from the first (group of families, nobis) 

 than they are from each other. 



Five species of monogenetic trematodes are known from four 

 or more species of fishes related to three genera of different families of 

 one order. 



The first of these species, Cathariotrema selachii (MacCallum) 

 is encountered on two species of Carcharhinus (Carcharhinidae) and besides 

 on Sphyrna zygaena (L. ) (Sphyrnidae) and Alopias vulpinus (Bon. ) (Lamnidae). 

 All three families are related to the order Lamniformes and are undoubtdly 

 consanguinous and represent one branch of the development of sharks 

 (Suvorov, 1948). 



The second species Tetraonchus borealis Olsson, is encountered 

 on two species of Salmonidae and two species of Thymallidae. The subject 

 of the consanguinous relationships of these two families of fishes was con- p. 231 

 sidered during the discussion of the occurrence of Discocotyle sagittata. 



The third species - -Gyrodactylus nemachili Bychowsky was dis- 

 covered on a number of species of Nemachilis (Cobitidae) and on three 

 species of carp-type fishes --Schizothorax pseudaksaiensis (Herz. ), Sch. 



argentatus (Kessl. ) and Phoxinus brachiurus Berg. In the work of Gvovzdev, 

 Agapova and Martehov (1953), in addition to that, the finding 



of G. nemachili on the perciformid fish Balarsch (in one individual) was also indicated, 

 but we do not take into consideration this indication that this worm was 

 accidentally transferred to the rapacious fish (perhaps it should read, we 

 do consider that this worm was accidentally transferred to the rapacious fish? 

 nobis ). The finding on Cyprinidae is obviously not accidental because we 

 (Bychowsky, 1936b) discovered G. nemachili on Sch. pseudaksaiensis, true 

 only on one individual, but then the authors indicated above discovered this 

 type on the Golian (the Phoxinus sp. , nobis ) in 61. 8% of the fishes and on 

 two species of Marinka, in one individual each. The relations between 

 Cobitidae and Cyprinidae are undoubtedly close, as has been indicated. 



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