It cannot be too strongly emphasized that any identification made with a key must be checked against an adequate description. The provision of a complete bibliography of original and subsequent descriptions is both beyond the scope of this work and unnecessary since all species described prior to 1939-1940 are dealt with by Lang (1948) and most marine species described in the period 1940-1969 are included in the catalogue of Bodin (1968, 1971). References are provided here only for species not included in these catalogues or for which there is important supplementary information.
Revisory work
is scattered through the literature, and is referred to where appropriate, but
mention must be made here of the vastly important paper of Lang (1965) in which
keys accurate to that date are given to many families and genera along with
important revisory notes and decisions.