place an accidental transfer to Cottus gobio . It was further established 

 that the first species is encountered on Trig la hi r undo Bl. , and the second 

 was discovered on Dactylopterus volitans L. (Palombi, 1949). Thus both 

 species must be placed in the speciesparasitizing one species of host each. 



Finally Capsala martinieri was discovered on Diodon sp. 

 (Diodontidae) and Mola mola (L. ) (Molidae), i.e., on representatives of 

 closely related families. 



Thus, the secondtype of the group of monogenetic trematodes 

 encountered on fishes of one order but of different families were analyzed. 

 Of the 37 species indicated in the literature, the analysis forces us to 

 exclude as incorrectly entered herein (in the group that parasitizes more 

 than one species of fish, nobis) and encountered actually only on one 

 species of fishes: Diplectanum aequans Wagener, Encotyllabe pagrosomi 

 MacCallum, Gyrodactylus medius Kathariner, Trochopus brauni Mola, 

 Megalocotyle zschokkei (Mola), Axine belones Abildgaard, and Gyrodactylus 

 fairporti Van Cleave. It is probable that one must also exclude as 

 erroneously indicated by the second type (genus, family) fishes (type of 

 relationship of the hosts, nobis ): Dactylogyrus inversus Goto and Kikuchi, 

 Microcotyle mouwoi Ishii and Sawada, and Tetrancistrum sigani Goto and 

 Kikuchi. Those three doubtful cases are based on the data of the same 

 work by Ishii and Sawada but unfortunately cannot be verified. Similarly 

 it is apparently necessary to exclude from the list of this group, Amphib- 

 della maccallumi Johnston and Tiegs, Ancylodiscoides varicus Ackmerov, 

 and Encotyllabe nordmanni Diesing as encountered only on one family of 

 fishes. The remaining 24 species are broken up into those encountered; 

 1) on two closely related families of fishes--12 species; 2) on three 

 closely related families of fishes --five species; 3) two closely related 

 families and one distant from the first- -one species [ Ancyrocephalus 

 mogurndae (Yamaguti)] ; 4) on relatively distant from each other, two -five 

 families of fishes--s"ix species [ Microcotyle ponnacanthi MacCallum 

 Ancyrocephalus nnanilensis Tubangui, Squalonchocotyle abbreviata 

 (Olsson), Trochopus tubiporus (Diesing), Pseudaxine indicana Chauhan and 

 HeterocotyJe minima (MacCallum)] . 



Thus we see that the basic mass of the species of this group is 

 encountered only on more or less related fishes although belonging to 

 different families of one order. 



We now pass to another group of species encountered in fishes p. 236 

 of different genera of one fannily, that is in some degree closely related to 

 each other. This concerns a considerably larger number of species --97, 

 that is almost twice as large as in both groups examined earlier. Of this 

 number, 41% falls among representatives of the genus Dactylogyrus --40 

 species. During the study of this genus by us almost 20 years ago 

 (Bychowsky, 1933a) we succeeded in showing that there is a regularity or 



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