of the classes Gyrocotyloidea and Cestoidea directly from. Monogenoidea. • 



This would have been completely untrue, but the common ancestors of both 

 apparently proceeded by way of adaptation to different peculiarities of 

 parasitizing. The possibility of transfer from the initial ectoparasitism. 

 toward endoparasitism in the group of cercomeromorpha indicates to us 

 certain peculiarities of the biology of the contemporary Monogenoidea. 



X 



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