An account of a collection of Euphausiacea and Mysidacea made in the waters of British Columbia by Miss A. A. Berkeley and Mr. G. H. Wailes, with summary of all previous records, so that the paper represents a complete account of the western Canadian species of these two groups of Crustacea, with a full list of references to the literature of west American species. Five species are described and figured as new to science, viz.: Pseudomma berkeleyi, Neomysis sculpta, Neomysis pseudomacropsis, Neomysis columbiae and Proneomysis wailesi.