Vol. 49, pp. 1-10 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON DESCRIPTIONS OF NEW INTERGENERIC HYBRIDS BETWEEN CERTAIN CYPRINID FISHES OF NORTHWESTERN UNITED STATES. BY LEONARD P. SCHULTZ and MILNER B. SCHAEFER.^ School of Fisheries, University of Washington. During the last eight years the senior author and numerous students in the school of fisheries, University of Washington, have collected fishes extensively throughout the Northwest. In many of these collections have appeared specimens which do not conform to published descriptions of any known species. They are either new species or hybrids. To demonstrate with absolute certainty that these specimens are hybrids, would require experimental crossing of the two supposed parents. This we have not done, but our abundance of circumstantial evidence, statisti-cally treated, indicates another clear case of hybridization in nature. Natural hybridization between different species and between different genera of fish probably is more common than usually believed. Hubbs and Schultz (1931 : 1-6), and Hubbs and Hubbs (1932 : 427-437), and others have observed natural hybridization. Each hybrid is treated separately below. I. A-pocope oscula carringtoni Cope x Richardsonius balteatus hydrophlox (Cope). The supposed hybrids, 19 in number, have been taken at the following localities in the State of Washington: Palouse River at Hooper, collected by L. P. Schultz and Leo Erkila, June 14, 1932; Palouse River at Palouse, collected by Schultz and Marvin Bowers on August 28, 1932; small tributary of the Palouse River 2 miles above Colfax, collected by Schultz and Erkila, June 18, 1932; South Fork Palouse River 2 miles above Pullman, collected by Schultz and Erkila June 15, 1932, and again on August 28, 1932, by Schultz and Bowers. iThe authors wish to thank Dr. C. L. Hubbs for the loan of some of the hybrids used n the preparation of this paper. 1— Peoc. Biol. Soc. Wash., Vol. 49, 1936. (1)
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