FIVE specimens of the monogenetic trematode described in this paper were obtained in the last quarter of 1953, at Trivandrum, from the gills of Anchoviella bataviensis (Hardenberg). The following description is based on the study of borax carmine stained balsam mounts of these specimens, regarded as a type s.eries. Two of them (Fig. 1 D & E) demonstrate only the extreme shortening and bulging of the body resulting from intense contraction of these highly muscular worms, while the others are moderately extended. The reproductive organs have been chiefly studied in A, probably a somewhat younger worm, since they are. less obscured by vitellaria, and there are fewer clamps than in B & C

gastrocotylid, engraulicola