Sympatric populations of S. malma and S. alpinus from Alaska were compared using a discriminant function analysis. The comparison indicated little or no hybridization. S. malma is, therefore, regarded as a distinct species. S. malma has fewer gill rakers, pyloric caeca and pores along the lateral line than S. alpinus. Five hundred specimens of S. malma from 42 North American localities were examined. Considerable geographic variability was observed. The variation showed no correlation with latitude. Evidence is presented that subspecific distinctions are invalid in S. malma. It is suggested that S. malma evolved in the North Pacific area sometime during the Pliestocene. / Science, Faculty of / Zoology, Department of / Graduate