Before inclusion in this study, all strains were tested to ensure that they possessed the common characteristics of the taxa under review. Thus they were shown to split glucose, mannose and trehalose, but not arabinose, fructose or xylose, and to produce arylsulphatase but not nitrate reductase. They were unable to hydrolyse Tween 80 or to reduce ferric ammonium citrate. The strains