. Bulletin of the British Museum (Natural History), Geology. . 185 Fig. 59 Pricyclopyge dolabra sp. nov. Upper Arenig, Fennian, B. rushtoni Biozone. a, holotype, exoskeleton with pygidium a little displaced and eyes poorly preserved, loc. 23, x 2, ; b, latex cast from cephalon, Capel-Dewi, x 6, GSM 3525; c, cranidium, locality as holotype, x 6, It. 19660; d, cast from mould of pygidium, locality as holotype, x 6, It. 18517. and the anterior part of the pygidial axis, but whether or not this segment was macropleural is unknown. The very narrow (tr.) first thoracic pleurae are probably r
. Bulletin of the British Museum (Natural History), Geology. . 185 Fig. 59 Pricyclopyge dolabra sp. nov. Upper Arenig, Fennian, B. rushtoni Biozone. a, holotype, exoskeleton with pygidium a little displaced and eyes poorly preserved, loc. 23, x 2, ; b, latex cast from cephalon, Capel-Dewi, x 6, GSM 3525; c, cranidium, locality as holotype, x 6, It. 19660; d, cast from mould of pygidium, locality as holotype, x 6, It. 18517. and the anterior part of the pygidial axis, but whether or not this segment was macropleural is unknown. The very narrow (tr.) first thoracic pleurae are probably related to the large size of the holotype, and largest P. binodosa eurycephala are little different. However, the posterior taper of the thoracic axis on P. dolabra is much less, so that at the fifth segment the pleurae are only just over half as wide as the axis; on P. binodosa eurycephala on the largest individual the pleurae are two-thirds as wide as the axis here, and relatively even wider on smaller specimens. The pygidium is incompletely preserved on the holotype, but shows a long, tumid axis with one ring defined, and three more indicated along the axial furrow. In view of the relatively wide proportions of the thoracic axis it seems reasonable to assign the pygidium shown in Fig. 59d to the species; it is generally more elongate, convex (tr.) and with narrower pleural regions than the pygidium of P. binodosa eurycephala. Pygidia of the latter are half as long as wide, or less, whereas the pygidium assigned to P. dolabra is two-thirds as long as wide. P. dolabra is clearly distinct from the P. binodosa group on most characters. Marek (1961) described P. obscura from the Llanvirn Sarka Formation of Bohemia, a species in which the length of the cranidium exceeds the maximum width of the median cephalic lobe, and with narrow, gutter-like palpebral rims. P. obscura is known only from the cranidium, although specimens attributed to P. binodosa by Horbinger & Vanek (1985) m
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