. Bulletin of the British Museum (Natural History). 96 COCKS & RONG. 37b 39 Fig. 35 Inversella {Reinversella) monensis Bates, 1968, exterior and counterpart interior moulds of brachial valve, holotype, the original of Bates 1968: pi. 8, figs 10-12, BB 30574, from Treiorwerth Formation (Arenig), 300 yards SE of Ffynnon-y-mab, Trefor, Anglesey, Wales, x 2. Figs 36-39 Spanodonta hoskingiae Prendergast, 1935, topotypes from Gap Creek Formation (Middle Ordovician), south side of Gap Spring, Price's Creek, Emmanuel Range, Western Australia. Fig. 36, lateral view of pedicle valve, BC 10
. Bulletin of the British Museum (Natural History). 96 COCKS & RONG. 37b 39 Fig. 35 Inversella {Reinversella) monensis Bates, 1968, exterior and counterpart interior moulds of brachial valve, holotype, the original of Bates 1968: pi. 8, figs 10-12, BB 30574, from Treiorwerth Formation (Arenig), 300 yards SE of Ffynnon-y-mab, Trefor, Anglesey, Wales, x 2. Figs 36-39 Spanodonta hoskingiae Prendergast, 1935, topotypes from Gap Creek Formation (Middle Ordovician), south side of Gap Spring, Price's Creek, Emmanuel Range, Western Australia. Fig. 36, lateral view of pedicle valve, BC 10604, x 3-5; Fig. 37, a brachial valve interior viewed obliquely from the posterior and straight down, BC 10605, x 3 and x 3-5; Fig. 38, brachial valve interior, BC 7238, x 4; Fig. 39, conjoined valves partly exfoliated to show the pedicle valve muscle field and part of the brachial valve platform, BC 7242, x 4. myophragm in brachial valve, but no brachial valve median septum. Remarks. The smooth shell surface (apart from peripheral parvicostellae and occasional rugae) is not known elsewhere in the family. It may be the result of silicification processes in the only known specimens, but if original then the cause is unknown, as is the function of parvicostellae generally. Species assigned Borua modesta Williams & Curry, 1985: 250, figs 169-175 from Tourmakeady Limestone (U. Arenig), Tourmakeady, Co. Mayo, Ireland. GUTTASELLA Neuman, 1977 1977 Guttasella Neuman: 31 Type SPECIES. Gurta^e/ZflgMfffl Neuman, 1977. Diagnosis. No rugae. No brachial valve median septum. Doubly geniculate like Inversella {Reinversella). Remarks. Guttasella is similar to Reinversella and differs externally in the lack of rugae. The cardinalia and shell shape indicate the placing of this genus within the Ahtiellinae. However, one of Neuman's illustrations (1977: pi. 5, fig. 4) indicates the slight trace of a bema, a feature which is. Please note that these images are extracted from scanned page images
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