Abstract
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.
