CHAPTER II 



A SHORT SURVEY OF THE SYSTEMS OF 

 MONOGENETIC TREMATODES 



In his "Classen and Ordnungen des Thier-Reichs" Braun p. 334 



(Braun, 1899-1893) expounds in considerable detail the history of the 

 classification of the monogenetic trematodes starting from Zeder 

 (Zeder, 1800) and ending with the exposition of the first variant of the 

 system of Monticelli (Monticelli, 1888). Braun himself accepts the 

 division of monogenetic trematodes into three "families',' Temnocephaleae 

 Haswell, Tristomeae Taschenberg, and Polystomeae Taschenberg. 

 As is known at the present time, the first "family" has no relation to 

 monogenetic trematodes. As regards the tAvo others, Braun divides 

 them into a number of "subfamilies. " We place both families and 

 subfannilies of Braun in quotations because the nanaes of his "sub- 

 families" correspond to the presently accepted designation of families, 

 and thus they also must be interpreted in the system of Braun. He 

 divides the "family" Tristomeae into three groups --Tristomidae 

 Beneden with 8 genera, Monocotylidae Taschenberg with 3 genera, and 

 Udonellidae Beneden and Hesse, with 3 genera. In contemporary views 

 of Udonellidae (Ivanov, 1952) this family comprised only two groups 

 characterized, plainly speaking, by the attaching disc being modified 

 into a sucker. All the remaining monogenetic trematodes are separated 

 by Braun into the "family'^ of Polystomeae subdivided into Octocotylidae 

 Beneden and Hesse with 9 genera, Polystomidae Beneden with 5 genera, 

 Microcotylidae Taschenberg with 4 genera, and Gyrodactylidae Beneden 

 and Hesse with 6 genera. The separation of Calceostoma Beneden, 

 Gyrodactylus Nordmann, Dactylogyrus Diesing and other monogenetic 

 trematodes into one "subfamily" attracts attention as well as the fact 

 that Octocotylidae are separated from Microcotylidae. This system 

 basically was retained until the beginning of the 20th century when 

 Monticelli (Monticelli, 1903) proposed a new classification which 

 represented a considerable step forward, both by quantity of the factual 

 material which . went into the basis of the system as well as by the 

 more precise grouping of this material. Characteristic is the exclusion 

 of the family of Temnocephalidae from this group of monogenetic 

 trematodes as animals with undetermined systematic status which was 

 new but completely correct. The basic common classification accepted 

 by Monticelli is mainly based on the nature of the structure of the 

 attaching apparatus. It is connpletely reproduced below. The subfamilies 

 which were elevated by him into the rank of families are marked by "n" 

 in parentheses, the new families--by "nn" and new subfamilies by an 

 asterisk. 



392 



