head structures which serve for attachment, but represent formations pe- 

 culiar to a large group of families of monogenetic trematodes Diclido- p. 2Z 

 phoridae, Mazocraeidae, Microcotylidae, etc. , see the systematic sec- 

 tion, page 402. One must note that in the work of Braun, mentioned in the 

 beginning of this chapter, the author points to the principal distinction be- 

 tween the first and second groups of the attachment organs of the anterior 

 end of the body of these animals, saying that the former and the latter are 

 in no way linked genetically, because sonne of thein appear as derivatives p. 23 



Fig. 16. Dionchus agassizi Goto, 

 youjig worm from the gills of 

 Rernora remora (L. ) from the 

 Indian Ocean. 



Fig. 17. Nitzschia sturionis 

 (Abildgaard), adult worn"! from 

 the buccal cavity of Huso huso 

 (L. ) Island of Sara (Caspian Sea). 



of the exterior layers and others appear as derivatives of the layers limiting 

 the buccal cavity. Unfortunately, this direct statement of Braun has not 

 been sufficiently taken into consideration by specialists in the group and this 

 oversight has led to connpletely arbitrary and wrong conclusions concerning 

 the interrelations of the different systematic groups. 



13 



