During a parasite survey of northwest Wisconsin fishes, a species of blood fluke of the genus Sanguinicola Plehn, 1905, was reported by the author (1947) from the mesenteric blood vessels of the largemouth bass, Huro salmoides (Lac.) and the northern smallmouth bass, Micropterus d. dolomieu Lac. In the 1947 paper, without naming or describing the fluke, it was declared a new species because it differed morphologically from the single known North American species, Sanguinicola occidentalis Van Cleave and Mueller, 1932, from the heart of the walleye, Stizostedion vitreum. The genus Sanguinicola was established by Plehn (1905) to receive S. armata and S. inermzis from European cyprinids; she called them endoparasitic Turbellaria. Later (1908), she reviewed her earlier conclusions and reclassified the two species as Cestodaria. Odhner (1911) correctly placed these forms in the Trematoda and discussed his and Looss' observations on the life cycle of S. inermis. The life cycle of this species was further clarified by Scheuring (1922). Woodland (1923) described a species of Sanguinicola from a Nile silurid, but did not name it. Odhner (1924) redescribed this species and named it S. chalmersi. S. intermedia was described by Ejsmont (1926) from European cyprinids. He also presented information on S. armata, S. inermis and S. chahnersi as well as additional life cycle data. Van Cleave and Mueller (1932) described S. occidentalis from a percid fish, the walleye (Stizostedion vitreum), in Oneida Lake, New York. More information on the biology and ecology of this species was presented by Van Cleave and Mueller (1934). Fischthal (1947) found S. occidentalis fairly widely distributed in the walleyes of northwest Wisconsin, and also reported this species from an additional percid host, the yellow perch (Perca flavescens). The present species was first observed April 15, 1944, when six adults were recovered from one of 11 Huro salmoides collected from Bear Lake, Barron County. On September 20, 1944, seven of 12 Huro salmoides from Lost Land Lake, Sawyer County. were found parasitized, two with one worm each and five with two each. Also on this date, seven worms were recovered from one of two Micropterus d. dolomieu from Lost Land Lake. On October 4, 1945, a fingerling Huro salmoides from Spring Creek, Washburn County, was infected with one worm. The author recalls finding in 1940 a single, typically triangular Sanguinicola egg in the ureter of Huro salmoides from the Huron River, Washtenaw County, Michigan. In all probability it belonged to the species herein described. The name Sanguinicola huronis is now proposed for this species. Its description is based on whole mounts of specimens fixed in AFA, stained in Ehrlich's acid haematoxylin, and mounted in balsam. The interpretation of the morphology presented many difficulties as encountered by other workers on the genus Sanguinicola.