Article: The Silurian trilobite Encrinurus punctatus (Wahlenberg) and allied species

The lectotype pygidium of Encrinurus punctatus (Wahlenberg), the type species, is from the Wenlock Series of the Island of Gotland, in which two allied species of Encrinurus are present; pygidia are not diagnostic but the size of the lectotype indicates that it should be attributed to the species with larger-sized individuals. An E. punctatus species-group is defined; conformity with the basic arrangement of tubercles on cranidium and pygidium is a necessary, but not sufficient, criterion of inclusion. The group includes also the following species: E. macrourus Schmidt, the smaller species from Gotland; E. tuberculatus (Buckland), a name revived for the British Wenlock form commonly referred to E. punctatus; E. stubblefieldi sp. nov. from the Ludlow Series of Shropshire; E. onniensis Whittard from the Upper Llandovery of Shropshire, and E. deomenos sp. nov. from the Jupiter Formation of Anticosti Island.