On the Anatomy and Systematic Position of the Causative Agent of So-Called Salmon Poisoning

Abstract

which they considered as the causative agent. The metacercariae of this parasite were found in the muscles and various organs of several species of salmonid fishes of the genera Salmo and Oncorhynchus caught in North American waters. The trematode was identified the following year (1926) by Chapin who considered it to be a new species of the family Heterophyidae, and named it Nanophyes salmincola. The generic name proved however preoccupied and was emended by Chapin (1927) to Nanophyetus.* Subsequently Nanophyetus salminicola was found by Cram (1926) in coyote (Canis lestes), raccoon (Procyon psora pacifica) and a lynx (Lynx fasciatus fasciatus), but it did not appear to be as pathogenic for these animals as for the dog. The only complete description of this trematode accompanied by a diagram of the anatomical structure is that given by Chapin (1926). While studying the original material t for the revision of Heterophyidae, I found some discrepancies between its anatomy and the previous description and illustration. It appears that Nanophyetus salmincola has no genital sucker or similar organ and no seminal receptacle and has a conspicuous cirrus pouch. The eggs proved to be much smaller than the suckers and not the contrary, as is shown on Chapin's illustration.