In order to know the final host ofCallotetrarhynchussp. observation was made of the contents of digestive tracts of 110 sharks of 10 different species collected in the Bungo Channel and adjacent seas. Scolecis of the cestoda were first found out in the valvular intestine of a hammerhead shark, Sphyrna zygaena, caught on April 29, 1970. The scolecis, however, occurred only at the terminal section of the spiral valve and half of them were moving into the colon without fixingwith tentacles to the spiral valve, which suggested that this shark had no aptitude for a final host of the cestoda. Adults and scolecis settled in the valvular intestine were detected in a specimen of Scoliodon walbeemi of about 2.2m in body length caught on October 31, 1970. The adults and scolecis numbered 62 and 21, respectively. Thus this species was thought to be one of the final hosts.Besides 593 adults and 74 scolecis were obtained from the valvular intestine of an unidentified shark caught on September 23, 1971.
A histopathological ovservation was made on a spontaneous lymphocystis disease which occurred in Lateolabrax japonicus (CUVIER and VALENCIENNES)in a fish farm pond at Kanzanji in Lake Hamana. The disease was first noticed in the early part of June, 1971 and continued till early September, 1971, when it came to an end. Part of affected fishes carried only on fins and the caudal trunk several small white warts which consisted of many lymphocystis cells. In serious cases, however, large masses of warts were found not only on the fins but also on various parts of the body surface, even on the eyes. From histological observation it was thought that lymphocystis cells in this species were originated from connective tissue cells of the skin. The lymphocystis cells had cytological features common to those described by WEISSENBERG and many other authors;that is, very large sizes, frequently over 400 μ in diamater, thick hyaline cellmembrane, large nucleus enriched with chromatic substance, large deeply basophilic nucloli, and deeply basophilic network-shaped inclusin bodies.
Three strins of nonmotile aeromonads were isolated in May, 1970 from lesions of 3 diseased specimens of Onchorhynchus rhodurus macrostomas(“Amago” In Japanese) which showed typical symptoms of furunculosis. Other 4 stpains were obtained in August, 1970 from lesions of 4 specimens of O. nerka adonis(“Himemasu”) showing furunculosis-like symptoms. These material fishes were all collected from ponds of the Shizuoka prefectural hatchery and trout laboratory at Fujinomiya in Shizuoka Prefecture. The strains were identified asAeromonas salmonicida, as their biological and biochemical characteristics were almost the same and closely resembled those of the strains ofA. salmonicida reported by EDDY in 1960.