Dr. Holló Ferenc szerk.: Parasitologia Hungarica 4. (Budapest, 1971)

tracted live from the intestinal system. Though investigations covered the entire body of the fish specimens, parasites were found only in the intestinal tract. The tapeworms were fixed in hot 10 % formalin and stained with hydrochloric acid carmine. The eggs were studied in Berlese solution, the slides stained with haematoxylin-eosin. Results Seven of the 14 examined eel specimens (Anguilla anguilla L.

) proved to be free of worm parasites. The other seven harboured a total of four parasitic worm species, namely two tapeworms, Bothriocephalus claviceps (Goeze, 1782) and Proteocephalus macrocephalus (Creplin.

1825), the opecoelid trematode Crowcrocoe- cum skr.jabini (Iwanitzky, 1928) identified by I. MATSKÁSI, and the camallanid nematode Camallanus truncatus (Rudolphi, 1814) identified by P. MÉSZÁROS. In some specimens the four Internal parasites occurred together, as commensal parasites. Three of the eels were only weakly parasitized (less than 10 parasite specimens), 2 eels moderately (10-50 parasites), and 2 intensely parasitized (more than 50 parasites present). Crowcrocoecum skr.jabini (Trematodes) and Camallanus truncatus (Nematoda) are widely distributed in other fish species of the Balaton (MATSKÁSI, 1967; MÉSZÁROS, 1968), whereas Bothriocephalus claviceps and Proteocephalus macrocephalus (Cestodes) arrived in the fauna by the introduction of the eels, in which they occur throughout Europe and even in America. The Proteocephalus macrocephalus haven't been reported yet from Hungary, Bothriocephalus claviceps was only remarked in enumerations or reviewed sketchily by EDELÉNYI (1963, 1969) and MOLNÁR (1966, 1970). As the morphology of the two tapeworms were studied unsatisfactorily by other authors (PREZE in 1965 gives accurate description of species P. macrocephalus

). we give the