Book excerpt: For many years the Keys have provided a working tool to those within the field and laboratory needing to know "what is this worm?" They have also helped to establish a classification, using associations of characters, that gives real insight into nematode relationships across the group and their lines of evolution. This supplementary volume is designed to complement the original CIH Keys, now reprinted as one volume, with the additional convenience of reordering into superfamily. The supplement includes revised and redescribed taxa and draws attention to new taxa, to generic level, published by many authors after the original Keys were complete. It also identifies the current position of some of the older genera not included in the original Keys.