Abstract

Lernaea elegans LEIGH-SHARPE, which is a commonly Japanese parasitic copepoda, known as "anchor worm", is found in the skin of Oryzias latipes (TEMMINCK et SCHLEGEL) -one of the commonenest fresh-water fish in Japan. In natural condition, it looks like a small yellowish green straw sticking into the skin of the host. The anchor-like horns of the cephalothorax penetrate into the muscle through the integument of the host. They sometimes reach to the pericardial or peritoneal cavities. The infected portions of the host are red from blood that continually oozed out and often growing into a gall. This paper deals with a histological study of the infected portions of the host and the life cycle of the parasite.