Air Br. in this context undoubtedly means air breathing snails (land snails and various intertidal and marsh snails fall into this category, as well as some fresh water snails) - these forms do not have gills, and instead breath by means of a specialized mantle cavity which acts (more or less) like a primitive lung. There is plenty written on dextral and sinistral ("right-handed" and "left-handed") snails, but I don't know what your notations "left whorl" and "right whorl" might mean here, because there is no correlation between direction of shell spiral and method of respiration. Paul M.