Due to the scanty description of Porambonites dentata Pander, 1830 and loss of its single type specimen, the name dentata has been subsequently attributed to various Ordovician to Silurian species of the genus Platystrophia s.l. with two costae in the sulcus and three on the fold.In The Natural History Museum, London, there is a complete shell identified presumably by Christian Pander himself as Spirifer dentatus from Pulkowa.That specimen is selected here as neotype to Platystrophia dentata, i.e. to a species, which on the basis of new material is restricted to the lower Darriwilian in the St Petersburg region.Considering differences in the interior of the dorsal valve, the other species (some with subspecies) of the so-called dentata-group, especially from the stratigraphically younger strata, are discussed and excluded from the material described here of P. dentata.
A new species of the gonambonitid genus Estlandia, E. hispida, is described from the lower part of the Upper Ordovician in Estonia and northwestern Russia (Ingria).The new species differs clearly from the most similar species E. marginata (Pahlen) in the external sculpture, in having less convex valves, and in the stratigraphical distribution.
T he Genus Glyptorthis Foerste, 1914 is a rare component of the Late Ordovician to early Silurian brachiopod faunas of the East Baltic. Hints and Röömusoks (1997) reported on the occurrence of Glyptorthis in seven stratigraphie levels within the Upper Caradoc, Ashgill and Llandovery, in a paper summarizing the stratigraphy of Estonia. To date, however, very few of these brachiopods have been studied in detail. Three species from the Ashgill and Llandovery were established by Rubel (1962) and Röömusoks (1970), whereas some unnamed Caradoc taxa were listed only in the latter paper. Collections made since 1987 by S. S. Terentiev and M. A. Zuykov revealed that rare specimens of Glyptorthis -like brachiopods occur in fossiliferous lower Caradocian (Idavere Regional Stage) strata in the western part of the St. Petersburg region, northwestern Russia. These specimens, assigned herein to a new glyptorthid genus and species Bassettella gracilis, comprise the core of this paper. Moreover, generic affinities of Estonian species from the Ashgill currently assigned to Glyptorthis are discussed. The type specimen of J. Hall (1847) in the American Museum of Natural History (New York) and specimens from the type area in the Sch¨chtert Brachiopod Collection in the Peabody Museum of Natural History, Yale University (New Haven), have been investigated for comparative purposes.
The enigmatic pentameride brachiopod Noetlingia Hall and Clarke, 1893 is revised and its stratigraphic range corrected. The type species Noetlingia tscheffkini occurs only within the upper Darriwilian (Ordovician) of the East Baltic and not in the Silurian as previously assumed. Thus, presently defined, the superfamily Porambonitoidea does not cross the boundary between the Ordovician and Silurian systems. Two other species occurring in the Lower to Middle Ordovician of South China and North America are assigned to Noetlingia.
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