Article: Eurydesma and Peruvispira from the Dwyka Beds of South Africa
Eurydesma mytiloides Reed 1932 and Peruvispira vipersdorfensis sp. nov. are described and figured. The distribution and origin of Eurydesma are considered. Eurydesma has been recorded from South Africa, India, Western and Eastern Australia, and South America: in all areas it is associated with deposits of glacial origin. It may have evolved from early Mytilacean forms and was apparently adapted to cold-water conditions and became extinct when these conditions ended. The characters of Peruvispira are discussed. It is separated from Ptychomphalina Fischer 1885, to which it is closely related, mainly by the possession of a distinct revolving concave area below the slit-band. Pleurocinctosa Fletcher 1958 is regarded as a synonym of Peruvispira. The fossils indicate a Lower Permian age, most likely Sakmarian but possibly early Artinskian.