Finally, the genus Microcotyle which contains a huge number 

 of species (at the present time 78 species of them have been described) is 

 encountered on 30 families related to three orders: Mugiliformes-- 

 Mugiiidae (2 species of Microcotyle) ; Polynemiformes --Polynemidae (1 

 species); Perciformes --Serranidae (9 species)., Priacanthidae (1 species), 

 Apogonidae (1 species), Sillaginidae (2 species), Latilidae (1 species), 

 Pomatomidae (3 species); Carangidae (4 species); Liognathidae (1 species); 

 Pomadasyidae {2-1 species); Sciaenidae (8 species); Lethrinidae (1 species); 

 Sparidae (17-16 species); Maenidae (1 species); Scorpidae (1 species); 

 Chaetodontidae (3-2 species); Cepolidae (1 species); Embiotocidae (2 

 species); Labridae (4-3 species); Trachinidae (2 species); Pholidae (1 

 species); Siganidae (3-2 species); Acanthuridae (1 species); Stromateidae 

 (3 species); Gobiidae (1 species); Scorpaenidae (3 species); Hexa- 

 grammidae (2 species); Platycephalidae (1 species Cybiidae (1 species). 

 The relations between three orders of the hosts of Microcotyle are undoubtedly 

 consanguinous. Thus, Jordan and Hubbs (Jordan and Hubbs, 1919) consider 

 that Mugiliformes derived from Perciformes particularly from the ancestors 

 of Apogonidae or Amplessidae. Finally, Polynemiformes, as is known, are 

 closely related with Mugiliformes (a number of authors include their only 

 fannily into one order with Mugilidae, see for instance Gregory 1951). 

 Thus we can consider that Microcotyle is encoiuitered basically on Perci- 

 formes and on two orders (families) of fishes related to them. 



_ 



It is interesting that in a mimeographed (B.B. has roto-worked, nobis ) 

 work of one Hawaiian researcher (W. A, Gosline, Unofficial Addendum to 

 the Recent Fish Sections in Berg's Classification of Fishes both Recent and 

 Fossile, 1948) possessed by A. N. Svetovidov Mugiliformes and Polynemi- 

 formes in Berg's scope (conaprehension, nobis) are included in the order of 

 Perciformes. Apparently this is incorrect, but demonstrates the degree of 

 similarity of all three orders. 



Before summarizing the totals of our analysis about the 

 occurrence of genera of monogenetic trematodes on the families of fishes, 

 which are their hosts, let us examine one nnore table (Table 15) analogous 

 to Table 4. During the composition of this table all the corrections made 

 in the preceding text are taken Into consideration, and 6 genera are excluded 

 (Anchylodiscus, Ancyrocephalus , Cleidodiscus, Diplectanotrem a, Tagia 

 and Urocleidus) for reasons indicated above. On first examination of Table 

 15 a relatively large number of genera of monogenetic trematodes .occurring 

 in representatives of two and m.ore families of fishes and relating not only 

 to one order--but to two different ones, becomes apparent. An impression 

 is created that the data of the tables speak for relatively insufficiently 

 close interrelationships between the occurrence of genera of Monogenoidea 

 on the families of fishes and the consanguinous relations of the latter. 

 Howevei, this is not so, and in order to be convinced of this we shall 



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