Studies on the brackish water cercariae in Japan. III. Three new echinostome cercariae in Tokyo Bay, with a list of Japanese echinostome cercariae (Trematoda).

The present paper reports three new echinostome cercariae with a review of known 18 spp. of Japanese echinostome cercariae. They were found from the brackish water snails collected from a muddy seashore at Urayasu during the past years from 1944 to 1952. One of these, Cercaria pseudo grani f era n. sp., bearing a strong resemblance to Cercaria grani f era Ogata, 1943, differed from it in detailed morphological features. Another species, Cercaria ophthalmoechinata n. sp. was a peculiar echinostome type in possession of one pair of eye spot. It was found on two occasions from the snail, T ympanotonus microptera. A third species, Cercaria yamagutii n. sp., characterized by possessing one pair of side branched excretory tube, was found in many occasions in 1944 but rapidly decreased the infection rate in subsequent years of investigation. Materials and methods were omitted here since they were given in details in the former papers of this series (Ito, 1956a; 1956b) .