In 1912 Odhner, studying the question of the homology of p. 336 



the female sex ducts among trematodes and tapeworms, at the same 

 time, came to the conclusion about the necessity of dividing the entire 

 group of monogenetic trematodes into two suborders or superfamilies 

 ("famile-clad") which correspond, in his opinion, to natural relations 

 within the limits of the group under study. He calls the first of these 

 suborders Monopisthocotylea and characterizes it by the presence of 

 a real vagina and the absence of a canalis genito-intestinalis and the 

 second- -Polyopisthocotylea by the presence of a ductus vaginalis and 

 a canalis genito-intestinalis (concerning Odhner's point of view on 

 homology of ducts, see page 71). At the same time dhner indicates 

 that if the family of Dicotylidae is to be transferred from Oligocotylea 

 Monticelli into Polycotylea then these artificial groups (as was also 

 noted by Monticelli) become natural and the first of them corresponds 

 to Monopisthocotylea and the second to Polyopisthocotylea. In the same 

 work Odhner indicates that it is inadmissible to consider only the data 

 on attaching organs as sufficient for systematization. Thus, according 

 to his opinion one should not attribute the genera, Polystonna(Poly- 

 stomidae) and Sphyranura (Dicotylidae) which are very close to each 

 other, to different families, which understandably for that time was 

 quite correct. In his opinion the internal organization can and must 

 be used as the first basis for systematics, whereas the external 

 structure (=the attaching armature)- -second. 



In 1922, Johnston and Tiegs (Johnston and Tiegs) in their 

 work on Australian monogenetic trematodes made an attempt at a new 

 classification of part of Monogenoidea and established a new super- 

 family- -Gyrodactyloidea (the separation of the systematic groupings 

 was performed by them within the limits of the superfamily). One 

 must note that in this work in addition to regroupings of what is known, 

 the description of a number of completely new forms is included 

 resulting in the possibility of establishing new families, subfamilies, 

 and genera. The superfamily Gyrodactyloidea of Johnston and Tiegs 

 embraces the 2nd, the 4th, and the 5th families in the system of 

 Monticelli plus a new family Protogyrodactylidae including two new 

 genera first discovered by the authors. The changes within the limits 

 of known families as a whole are not very considerable. Thus, within 

 the family Gyrodactylidae the subfamily Diplectaninae is abolished, in 

 connection w^ith the fact that the genus Diplectanum is considered as a 

 synonym of the genus Ancyrocephalus, ana two new subfamilies are 

 included, of which Lepidotreminae is completely new and Merizocotylinae 

 is transferred from the family Monocotylidae. Further, the family 

 Monocotylidae is subjected to changes, within the limits of which the 

 subfamily Anisocotylinae, the genera of which partially pertain to 

 Gyrodactylidae (subfamily Merizocotylinae --is a part of Anisocotylinae) 



395 



