. Bulletin of the British Museum (Natural History), Geology. ARENIG IN SOUTH WALES 89 -r 21 100 metres. Fig. 7 Map showing proposed stratotype for the base of the Fennian Stage, northeast of Whitland Abbey (see Fig. 2). The trilobites are dominated by cyclopygids, especially Pricyclopyge, and by the atheloptic assemblage of blind or small-eyed benthonic forms described below. The trinucleids Bergamia and Stapeleyella are typical of the stage, although both extend upwards into the Llanvirn. The Fennian includes at least part of the /. gibberulus and all the Didymograptus hirundo graptolite bioz
. Bulletin of the British Museum (Natural History), Geology. ARENIG IN SOUTH WALES 89 -r 21 100 metres. Fig. 7 Map showing proposed stratotype for the base of the Fennian Stage, northeast of Whitland Abbey (see Fig. 2). The trilobites are dominated by cyclopygids, especially Pricyclopyge, and by the atheloptic assemblage of blind or small-eyed benthonic forms described below. The trinucleids Bergamia and Stapeleyella are typical of the stage, although both extend upwards into the Llanvirn. The Fennian includes at least part of the /. gibberulus and all the Didymograptus hirundo graptolite biozones (see Fig. 11, p. 100). Jackson (1962) recognized the D. hirundo Biozone in the Lake District more from the abundance of biserial graptoloids than from the presence of the eponymous species. As Jenkins (1982) has observed, the ranges of D. hirundo and /. gibberulus overlap, and both can be found below the range of biserials. On Jackson's criterion, only the highest part of the Fennian (Dionide tevigena Biozone) in the Llanfallteg Formation of south Wales would conform to his usage of the Didymograptus hirundo Biozone. The range of D. hirundo certainly extends down into the Bergamia rushtoni trilobite Biozone, and it is this fauna which includes identical trilobite species to those at Randel Crag in the Lake District. It is. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original British Museum (Natural History). London : BM(NH)
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