armature (Fig. 190) is represented by 12 lateral hooks and 2 middle hooks 

 which have the characteristic shape with already developed interior and 



p. 172 



exterior offshoots. 



The sizes of edge hooks are 0. 012 - 0. 014 mm, the 



sizes of the middle ones are 0. 010 - 

 0.011 mm. During subsequent 

 development the nniddle and edge 

 hooks stop growing and among the 

 adult individuals they have the same 

 dimensions. We shall also indicate 

 that during the time of development 

 the growth of the eyes does not take 

 .place and it is possible that among 

 the adults they are reduced (disappear? 

 nobis ) because we were not able to 

 find traces of eyespots among certain 

 adult individuals. 



O.OInf* 



Fig. 189. Calceostomella inermae Fig. 190. Calceostomella inermae 



(Parona and Perugia), young worm 

 from the fins of Corvina nigra Salv. 

 from the Bay of Naples (Mediter- 

 ranean Sea). 



(Parona and Perugia), attaching 

 armature of a free-swimming larva. 



12. The development of Tetraonchus Diesing 



Among the representatives of the genus Tetraonchus (Fig. 64) 

 the presence of 4 eyes, of a pipe -shaped intestine and of an attaching disc 

 with 16 edge and 14 middle hooks is characteristic; the latter are linked 

 with each other by a single connecting plate. 



In August of 1949 on the Island of Hanka, A. V. Gussew 

 hatched a considerable number of larvae from the eggs of T. monenteron 

 (Wagener) which parasitize the gills of Esox reicherti Dyb. The develop- 

 ment of larvae within the eggs continued about 3 to 4 days. A number of 

 the hatched larvae were impregnated with silver. We also hatched larvae 

 of T. monenteron (Wagener) from the eggs of worms from Esox lucius L. 



185 



