of Microcotylidae (Fig. 23) which, nevertheless, differs in its structure, 

 on the one hand in connection with the asymmetry of the disc in a number 

 of forms as for instance (Axine, Fig. 9) and on the other hand, as a result 

 of more complex relations with the body of the animal (see page 439 ). 

 Finally, the discs of Acanthocotylidae (Fig. 18, A) represent the last group 

 of attaching discs which have a secondary origin, while the primary disc 

 remains non-functional, lying on the secondary one (see page 383 ). 



p. 27 



Imm' 



Fig. 27. Monocotyle myliobatis Taschenberg, 

 adult worm. Magnified 20 times. (According 

 to Palombi, 1942). 



Fig. 28. Trochopus pini 

 (Beneden and Hesse), adult 

 worms from the gills of 

 Trigla lucerna L. from 

 the Bay of Biscay (Atlantic 

 Ocean). 



The attaching organs lying on the disc can be divided into groups 

 of chitinous and muscular formations; however, the latter are not en- 



_ 



As regards the term "chitinous" we must explain that by this term is 

 nneant the physical consistency of the fornnations and not their chemical 

 constituency because at the present time this has not been elucidated. 

 Our own efforts to do this were unsuccessful. 



19 



