TWINS AND SALMON; TWINS AND VEGETABLES. On page 37 his article (“Toward the Intellect”), Levi-Strauss says that the particular relationships which the Nuer people establish between twins and birds are closely paralleled by the relationship which the Kwakuitl of British Columbia conceive of between twins and salmon.
Google also called my attention to an article by Raymond Firth: “Twins, Birds and Vegetables: Problems of Identification in Primitive Religious Thought”.