Palaeozoic stromatoporoids comprise an extinct class of non-spiculate poriferans that are represented as fossils by their basal carbonate skeleton. A revised terminology for the description of these fossils is presented. Seven orders (Labechiida, Clathrodictyida, Actinostromatida, Stromatoporellida, Stromatoporida, Syringostromatida, Amphiporida) are recognized. The following is recorded for each genus: (1) type species, catalogue number and depository of the primary holotype; (2) synonyms and their type species; (3) diagnosis; (4) stratigraphic range; (5) estimate of the number of species assigned to the genus; (6) stratigraphic and geographic distribution of the genus. Problems in the definition and recognition of the genus are briefly discussed in annotations. One hundred and nine genera are considered valid, or doubtfully valid. Fifty three genera are placed in synonymy. An additional 14 genera are considered to be of uncertain placement in the classification.

Key words: Stromatoporoids, Porifera, taxonomy, morphologic terminology, Palaeozoic, distribution.

Colin W. Stearn [colinst@golden.net], Earth & Planetary Sciences, McGill University, present address: 65 Aberdeen Road, Kitchener, N2M 2Y4, Canada. Barry D. Webby [bwebby@laurel.ocs.mq.edu.au], Centre for Ecostratigraphy and Palaeobiology, Earth & Planetary Sciences, Macquarie University, North Ryde, NSW 2109, Australia. Heldur Nestor [hnestor@gi.ee], Institute of Geology, Tallinn Technical University, Estonia pst. 7. Tallinn, EE0001, Estonia. Carl W. Stock [cstock@wgs.geo.ua.edu], Department of Geology, University of Alabama, Box 870338, Tuscaloosa, AL. 35487-0338, U.S.A.