Article: The British Carboniferous species of Girvanella (calcareous algae)
The type specimens, or topotypes, of the known species of Girvanella from the Lower Carboniferous rocks of Britain are redescribed. The two species found in the Girvanella Band in northern England are identical with those described by Wethered from the Avon Gorge, which occur at a very similar horizon. It is shown that the type of preservation and the amount of decay before burial affects appearances of the specimen in thin section, blurring specific characters. Various growth-forms of a species may be recognized, but such forms do not seem to be of value for stratigraphic work.