Thus, from the existing incomplete material on the develop- 

 ment, more precisely according to the larvae, it is apparent that in 

 Ancyrocephalus the situation is much more complex than among the pre- 

 ceding types. Thus, from the seven species which have been examined. 



0.01 HM 



001mm 



Fig. 161. Ancyrocephalus (s. lat. ) Fig. 162. Ancyrocephalus {s. lat. ) 



pavlovskyi Gussew, attaching 

 armature of the free -swimming 

 larva. (According to Gussew, 

 1955). 



pavlovskyi Gussew, attaching 

 armature of the disc of an adult 

 worm from the gills of Hemibarbus 

 maculatus Bl. (According to 

 Gussew, 1955). 



on three the middle hooks are incepted in the postembryonic period, 



whereas among five (sic) species the inceptions of the first pair of 



middle hooks are already formed at that time. In one species the connecting 



plate of the ventral (first, pair) of the middle hooks is also incepted in the 



embryonic period. The fate 



of the edge hooks also varies. 



Among 4 species they remain ^ ^ 



without change during the ^^^\^ 



entire life of the worms, 



whereas, among three species 



DO 1mm 



Fig. 163. Ancyrocephalus 

 (s. lat.) hemibarbi Achmerow, 

 attaching armature of a free- 

 swimming larva. (According 

 to Gussew, 1955). 



Fig. 164. Ancyrocephalus (s. lat.) 

 hemibarbi Achmerow attaching arma- 

 ture of the disc of an adult worm from 

 the gills of Hemibarbis maculatus Bl. 

 (According to Gussew, 1955). 



they grow more or less intensively during the postembryonic period. It 

 is impossible not to note that among forms which have hooks which do not 

 grow, in a majority (among 3 out of 4), the middle hooks are incepted 



168 



