Actinocleidus Mueller, 1937; Anchoradiscus Mizelle, 1941; Anchylo - 

 discus Johnston et Tiegs, 1922; Ancylodiscoides Yamaguti, 1937; 

 Ancyrocephaloides Yamaguti, 1938; Bychowskyella Achmerow, 1952; 

 Cleidodiscus Mueller, 1934; Daitreosoma Johnston et Tiegs, 1922; 

 Diplectanotrema Johnston and Tiegs, 1922; Empleurosonna J ohnston et 

 Tiegs, 1922; Haliotrema Johnston et Tiegs, 1922; Hamatopeduncularia 

 Yamaguti, 1953; Heteronchocleidus Bychowsky, 1956; Meta haliotrema 

 Yamaguti, 1953; Murraytrema Price, 1937; Pseudohaliotrema Yamaguti 

 1953; Pseudohaliotrematoides Yamaguti, 1953; Pseudomurraytrema 

 Bychowsky, 1957; Parancyrocephaloides Yamaguti, 1938; Proancyro - 

 cephalus Bychowsky, 1957; Rhabdosynochus Mizelle et Blatz, 1941; 

 Tetrancystrum Goto et Kikuchi, 1917; Urocleidus Mueller, 1934; 

 ? Anoplocotyle P olombi, 1943. 



The descriptions of various separate genera are very in- 

 adequate, especially since some of them were encountered only once 

 and were poorly studied. First of all, this concerns even such important 

 peculiarities as the number of edge hooks and the structure and presence 

 of the connecting plates of middle hooks. Thus, the number of edge 

 hooks among Ancylodiscoides was indicated as different by different 

 authors. Yamaguti (Yannaguti, 1937b) wrote that there are only five 

 hooks, Siwak (Siwak, 1932)--12, Zandt (Zandt, 1924--16, whereas 

 actually there are 14 which is shown by numerous data in our re- 

 searches and that of our collaborators (we have also examined the type 

 species, see also: Bychowsky and Nagibina, 1957). According to 

 Yamaguti, there are 5 edge hooks in the only species of the genus 

 Ancyrocephaloides/whereas our verification of material from the same 

 region of research showed that there are 14 of them, just as among 

 other Ancyrocephalinae. At the same time the indication of the absence 

 of connecting plates of middle hooks in the diagnosis of the genus p, 349 



Ancyrocephaloides is incorrect. Actually, there are 4 of them although 

 they are very weakly developed and indisputably reduced as a result of 

 the division of each of the two customary plates into two parts as is 

 observed, for instance,annong certain species of Ancylodiscoides . 

 According to our verification of the factual material it appeared also 

 that 14 edge hooks also exist among Empleurosoma (the authors in- 

 dicated 2 hooks) and Tetrancistrum (according to the author the edge 

 hooks are absent altogether, whereas Price, who discovered these 

 hooks first, could not ascertain their exact number). 



The only genus rennaining without verification is Daitreosoma , 

 it probably also has 14 edge hooks and not 2 as is indicated by the 

 author. 



413 



