Systematics, biostratigraphy and significance of discoid and partly discoid corals from the Devonian of northwestern Canada, Ural Mountains Russia and southeastern Australia

Abstract

“Hamilton group” of the region of Mackenzie River and Porcupine River Russian America, were named and briefly described by Meek in 1868. Their collection before that date in remote land-locked areas inevitably means that the localities provided could only have been very approximate. Both species were based on a single specimen and placed in the Museum of the Smithsonian Institution, now the United States National Museum. The specimen from Alaska, named Palaeocyclus kirbyi is lost (Bassler 1937, p. 190). Since no additional material is available the species is mentioned in the present work only as a questionable synonym of Meek’s other 1868 species. The holotype of Meek’s second discoid coral, named Combophyllum multiradiatum, is extant but is severely water-warn and is from an unknown formation and local ity. With access to about 20 collections cont aining C. mul t i radiatum, some from carefully measured stratigraphic sections, it has been possible to re-interpret the lithoas well as the biostratigraphy of C. multira diatum. More than a hundred specimens of the species have been identified, providing new data on its variable morphology. Although the family and genus status have changed, no formal taxonomic treatment has become available since the species was proposed one and a half-centuries ago. Published comments are restricted to Bassler’s comments that the holotype is a water-worn circular disc, 18 mm wide, about 3 mm thick and that it belongs to Microcyclus, and McLaren’s observation (1962, p. 12) that longitudinal sections of the species show it to be correctly identified with the Hadrophyllidae. After discussion of the Hadrophyllidae the present work raises one of its previously constituent sub -