Fig. 32. Different types of middle hooks of A- - Dactylogyrus anchoratus 

 (Dujardin); B--D. alatus Linstow; C--D. wunderi Bychowsky; 

 D--Mazocraes alosae Hermann; E--Gyrodactylus medius Kathariner; 

 (from the first pair) F--Diplozoon paradoxum Nordmann; G--Octostoma 

 sconnbri Kuhn (from the second pair); H--Nitzchia sturionis (Abildgaard) 

 (fronn the third pair); I--Dasybatotrema dasybatis (MacCallum); 

 J--Thaumatocotyle dasybatis MacCallum. The sizes in relation to each 

 other are disregarded. 



Fig. 33. Different types of connecting plates of the middle hooks. 

 A--Dactylogyrus anchoratus (Dujardin); B--D. simplicimalleata Bychowsky; 

 C--D. drjagni Bychowski; D--D. longicopula Bychowski ; E--D. crypto - 

 naeres Bychowski; F--D. wunderi Bychowsky; G--D. kulwieci Bychowsky; 

 H--Gyrodactylus arcuatus Bychowski; I- - Tetraonchus monenteron 

 (Wagener). 



then-i to the attaching disc itself. The shape, the sizes, the number and 

 their relative position are varied. Among various forms the number of 

 middle hooks can fluctuate from one pair up to three pairs (just as edge 

 hooks, basically this is a symmetrically arranged formation). Middle 

 hooks can also be absent (as for instance in Acolpenteron, Fig. 44). 



22 



