This remark does not pertain to certain of the highest Monogenoldea (see 

 page 425 ). 



secondary phenomenon among the majority of the Monogenoidea which have 

 no eyes, nevertheless the presence of the given characteristic among 

 Amphibdella hardly has the same nature, especially since we never did find 

 a trace of eye pigment which usually occurs among a majority of other 

 forms, even among the youngest individuals of the genus. It seems to us 

 that for the present genus this is a more ancient characteristic underlying 



01 MM 



Fig. 285. Amphibdella torpedinis Chatin, attaching disc from the worms 

 from the gills of Torpedo marmorata Risso from Arcachon Basin (Atlantic 

 Ocean). A--of the young (but mature!) worms; B--of the adult worm. 



its relatively old separation from other Monogenoidea. The latter also 

 confirms, to a certain degree, the occurrence of Amphibdella on a group 

 of very isolated hosts - -electric skates. Although it was indicated by us in 

 the diagnosis that the remaining basic characteristics of the famiily are 

 similar to Tetraonchidae it is only true in general traits, but the separate 

 traits of the structure of the cephalic and the copulatory organ, of the 

 vitellaria etc. , also attests to the considerable peculiarity of Amphibdella. 

 All this taken together forces us to consider the separation of this 



genus into an independent family as quite proper. 



p. 394 



3. Family Tetraonchoididae Bychowsky, 1951 



(Fig. 29) 



Tetraonchidea, having middle sizes in the adult state. The 

 attaching apparatus consists of a sucker-shaped attaching disc having a 

 chitinous armature consisting of 16 edge hooks, one pair of middle hooks 

 and a special supporting plate lying near the central part of the disc; the 



471 



