Microscopic images of specimens of Neoechinorhynchus johnii from Eleutheronema tetradactylus, Johnius carouna, and Otolithes ruber in the Pacific Ocean off Vietnam. (13) The anterior end of a male specimen showing the typical dorsal curvature and humping. (14) The anterior proboscis showing its characteristic curvature at the base and the prominent posteriorly directed root (arrow). (15) An anterior trunk section showing the para-receptacle structure (arrow) penetrating into the posterior receptacle wall near the large cephalic ganglion. (16) The male reproductive system of a young specimen. (17) The posterior end of a female reproductive system with a typical expanded curved vagina and a subventral gonopore. (18) Another typically convoluted posterior end of a female reproductive system. (19) An image showing an often-observed constriction at the posterior tip of a female trunk. (20) A rare image of the two types of eggs in the same frame, the spheroid egg and the lantern-like egg.