Abstract
The reproductive emergence of Philometroides seriolae (ISHII, 1931) YAMAGUTI, 1935(nematode) from the yellowtail, Seriola quinqueradiata, was observed in a large exhibition tank of the Ohita Marine Palace from the middle of August to the beginning of September, 1969. From the observations the following process was suggested. A matured P. seriolae comes out from the interior of the fish body through a small hole made in the skin and hungs down from the hole for a few weeks or more by Ieavng one end of the body under the skin. The part of the worm body exposed to the outside loses elasticity and color and flattens. The end of the exposed part collapsed and thus the larvae are released. and scattered about widely owing to the swimming of the host. The number of the larvae carried by a mother worm varies with the size of the worms, being about 6 to 8 millions in worms measured over 30cm in length.
