On Glyptograptus dentatus (Brongniart) and some allied species

The original specimens of Brongniart's Fucoides dentatus can no longer be traced and must be assumed lost. It is therefore proposed that one of the originals of Hall's Diplograptus pristiniformis be taken as the neotype, and the species is defined with reference to this and redescribed. A new species believed related to G. dentatus is described from the Arenig rocks of Britain; G. austrodentatus Harris and Keble is redescribed; and four new varieties are recognized from Britain, Scandinavia, and North America. The relations of the G. dentatus and G. austrodentatus groups are discussed, and three other British species are described (two new and one new to Britain) which, though previously identified as G. dentatus, are here assigned to different genera.