During the analysis of the fauna of the monogenetic trema- 

 todes of Cypriniformes we see first of all that it is very different in 

 its origin and this also pertains to its representatives belonging to the 

 same family. Thus, the fauna of Dactylogyridae is composed of 18 

 genera, part of which are very numerous; apparently in a nunaber of 

 cases their origin is not linked with each other and thus among the 

 family we encountered both the primary and the secondary, phylo- 

 genetically, parasites of Cypriniformes. Attention is attracted to the 

 fact that within the limits of the Cypriniformes all genera of Dactylo- 

 gyrinae without exception are encountered only on Cyprinidae, 

 Catostomidae, Cobitidae, Characinidae, i.e., only on Cyprini and 

 only in fresh and brackish waters with the single exception of 

 Dactylogyrus iwanowi Bychowsky, (see page 110). Without any doubt 

 this subfamily has fresh water origin just as their primary hosts; 

 however, along with the indicated families of fishes, Dactylogyrinae 

 are also encountered on others related to other orders--Perciformes, 

 Anguilliformes, and Gasterosteiformes. Nevertheless, in the cases 

 which serve as examples of the transfer from the primary hosts we 

 deal only with fresh water fishes or the ones which became adapted to 

 life in fresh water. A different situation exists with the representatives 

 of Anchyrocephalinae. Their basic part is also undoubtedly fresh water 

 (as for instance, nobis) the genera Cleidodiscus , Urocleidus, Pseudo - 

 murraytrema, Ancylodiscoides, and Bychowskyella, Another small 

 part is known only from nnarine waters and parasitizes Cypriniformes 

 which became secondarily adapted to life in marine bodies of water 

 and on marine perciformids. Here belongs the genus Ancylodiscus 

 parasitizing Plotosidae and Gadopsidae (see page 253 ). Finally one 

 genus, Ancyrocephalus , contains species encountered both on fresh 

 water Cypriniformes (Cyprinidae, Cobitidae) and possibly marine 

 (Ariidae, see page 222 ; Ancyrocephalus alatus Chauhan); which, in 

 addition to that, is known from a small number of different orders of 

 marine fishes. As was already indicated, this genus is artificial (see 

 page 264), consequently it is difficult to utilize it for analysis. One 

 can only say about it that its few representatives on Cyprinifornnes 

 became adapted to parasitizing these fishes secondarily and descend p. 310 



fronn species peculiar to other orders of hosts. As a whole, the 

 Ancyrocephalinae are also encountered on 9 orders of predominantly 

 marine fishes besides the Cyprinifornnes, consequently the question 

 of their origin cannot be studied only by the analysis of the fauna of 

 Cypriniformes. We shall analyse it in detail later but now, running 

 ahead, we shall only indicate that what seems to us as more probable 

 is the fresh water origin of Anchyrocephalinae, and that at the same time 

 a part of the genera of this subfamily is linked phylogenetically with 

 Cypriniformes primarily and part--secondarily (see page 456 ). Thus, 

 it is possible to suppose that Dactylogyridae as a whole are primarily 



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