Cercaria owreae (Hutton, 1954) is renamed and redescribed. It has two posterior appendages and represents a new type of distome cercaria, named “Diplocercous”. The caeca extend into the appendages, one into each, and a rosette-like group of six diverticula occurs at the anterior end of each of them. Certain peculiarities of the caecal epithelium are described and discussed briefly, but because of the immature state little information can be given about other organs. Fifteen larvae were obtained from 12 out of 181 Sagitta hexaptera collected in four Caribbean localities. Two larvae were found in the gut, the remainder in the coelom. The trematode probably belongs to the Accacoeliidae and is referred tentatively to the genus Accacladocoelium Odhner, 1928, adults of which are parasites of the sunfish Mola mola (L.).