middle hooks and one connecting plate. Intestine with 2 trunks ending blindly, 

 without lateral outgrowths. Copulatory organs chitinous, consisting of a 

 pipe and a complex supporting apparatus. There are no eyes. Other charac- 

 teristics as among Tetraonchidae. 



Parasites of marine Elasmobranchii (Torpedinidae). 



Type and only genus, Amphibdella Chatin, 1874, (Fig. 284). 



In addition to the type genus a very close genus, Amphibdelloides 

 Price, 1937, the independence of which cannot be confirmed on the basis of our 

 data, was described. 



To clarify the contradictory and inaccurate data of preceding 

 authors we collected and examined considerable material from Torpedo 

 marmorata Ris. and T. ocellata Raf. from the Mediterranean Sea (Bay of 

 Naples) and the Atlantic Ocean (Bay of Arcachon), from_T_. californica Ayr, p. 391 

 from the Pacific Ocean (Shore of California) and fromJT. smithi S. from 

 the Arabian Sea (near Beluchistan). First of all it was necessary to ascertain 

 the true number of edge hooks of the attaching disc which are of principal 

 significance. As is known, Chatin- -the author of the genus Amphibdella , 

 did not see the edge hooks at all. Parona and Perugia (Parona and Perugia, 

 1890b) indicated the presence of 6 pairs, Ruszkowski (Ruszkowski, 1931) 

 found 8 pairs of them and in the re'sumes' of Price and Sproston (Price, 

 1937b; Sproston, 1946) a new nuinber is cited--7 pairs. Actually, as our 

 verification confirmed, the number of edge hooks in Amphibdella is 8 pairs 

 as was first indicated correctly by Ruszkowski and then confirmed by 

 Palombi in his re'sume'of monogenetic trematodes of Italy (Palombi, 1949). 

 Thus, the genus Amphibdella, by that characteristic alone, falls out of the 

 family of Dactylogyridae to which it has been ascribed until the present 

 time. The second uncertain question was the presence and the number of 

 the connecting plates between the middle hooks of the disc. Thus, Chatin 

 who described the genus does not indicate the presence of middle plates. 

 Parona and Perugia in two important works published in the same year 

 (Parona and Perugia, 1890a, 1890b) at first indicate the presence of one 

 plate and give the corresponding drawing, and then speak about the presence 

 of two plates among small specimens of Amphibdella showing this in a 

 special drawing, and at the same time write that the larger samples do not 

 have a single plate. Palombi (Palombi, 1949) confirms that the large 

 individuals of A, torpedinis are deprived of connecting plates and smaller 

 individuals have, according to his data, only one plate --which as a matter 

 of fact he does not show. In a special note Palombi writes in addition to 

 this that he examined the collections of Parona and not once did he find 

 individuals with two connecting plates, although all the authors write that 

 they are clearly and always visible among small worms. Price (Price, 

 1937b) divides the genus Amphibdella into two on the basis of the presence 

 or absence of the connecting plates and also of the "lobed" or "unlobed" 



468 



