Llandovery brachiopods from Wales with special reference to the Llandovery district

The paper is intended primarily as a palaeontological supplement to the stratigraphical studies of the Llandovery rocks in the type area (O. T. Jones 1925, 1949). The systematic revision is therefore based on collections obtained from the Llandovery district but material, in certain instances, has also been described from the Llandovery rocks of Meifod and Haverfordwest. Thus the basal beds (Ax) of the Llandovery district are unfossiliferous, whereas the equivalent rocks in Meifod and Haverfordwest are richly fossiliferous and so provide important links between the Llandovery and the Ordovician brachiopods. Furthermore, some forms, especially those from the prolific Gasworks Sandstone of Haverfordwest, are better preserved than contemporaneous ones from Llandovery and have been used for specific descriptions.

The systematic study includes emended descriptions of nine species and the erection of two new genera, one new subgenus, eleven new species and fourteen new subspecies. Such a revision may seem radical, but it must be borne in mind that the fauna has received little attention in the past, and actually this work is intended only as the beginning of a much fuller investigation.

The paper concludes with a faunal list to show the stratigraphical distribution of Llandovery brachiopods. The chart emphasizes the fact that each of the lithological divisions established for the Llandovery district contains a diagnostic faunule.