. Bulletin of the British Museum (Natural History), Geology. 208 R. A. FORTEY & R. M. OWENS Remarks. The general relationships between Furcalithus and other contemporaneous tri- nucleines are discussed above. Main differences from Myttonia are: presence of girder and radially aligned pits around entire fringe (apart from proterolateral corners); from contempora- neous Bergamia species, Furcalithus differs in the lack of deep sulci, presence of more I arcs, presence of interradii in the I series and a narrower pygidial border onto which the axis does not extend. However, the Llandeilo Berga
. Bulletin of the British Museum (Natural History), Geology. 208 R. A. FORTEY & R. M. OWENS Remarks. The general relationships between Furcalithus and other contemporaneous tri- nucleines are discussed above. Main differences from Myttonia are: presence of girder and radially aligned pits around entire fringe (apart from proterolateral corners); from contempora- neous Bergamia species, Furcalithus differs in the lack of deep sulci, presence of more I arcs, presence of interradii in the I series and a narrower pygidial border onto which the axis does not extend. However, the Llandeilo Bergamia species B. prima and B. whittardi (Hughes 1971: 140 and 146 respectively) have more pits in the I series than do earlier ones, and in this respect resemble Furcalithus. However, interradii are absent and the pygidium has the typically broad border of Bergamia; the similarity of the fringe is presumably the result of convergence. Furcalithus radix sp. nov. (Figs 74a-e, 75) Holotype. It. 18949, dorsal exoskeleton lacking lower lamella and genal spines. Type locality and horizon. Whitlandian Stage, Furcalithus radix Biozone; about 70 m above base of Afon Ffinnant Formation, Cwm yr Abbey, loc. 16K. Paratypes. , NMW , b-14a, b, all from basal 100m of Afon Ffinnant Forma- tion, Cwm yr Abbey, loc. 16L. Stratigraphical range. Whitlandian, F. radix Biozone, basal 100 m of Afon Ffinnant 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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