. Bulletin of the British Museum (Natural History). 18 A. J. BECKLY a. Fig. 17 Calymenella preboiselli sp. nov. a, cranidium with free cheek replaced, b, free cheek in plan view, c, lateral view of reconstructed cephalon. (All approx. x3). Genus CALYMENELLA Bergeron, 1890 Type species. Calymenella boiselli Bergeron, 1890. Calymenella preboiselli sp. nov. Figs 16a-h; 17a-c Diagnosis. Calymenella very similar to type species in having elongate sub-triangular anterior area, but differing from this and other species in having less strongly developed lateral, preglabellar and occipital fu
. Bulletin of the British Museum (Natural History). 18 A. J. BECKLY a. Fig. 17 Calymenella preboiselli sp. nov. a, cranidium with free cheek replaced, b, free cheek in plan view, c, lateral view of reconstructed cephalon. (All approx. x3). Genus CALYMENELLA Bergeron, 1890 Type species. Calymenella boiselli Bergeron, 1890. Calymenella preboiselli sp. nov. Figs 16a-h; 17a-c Diagnosis. Calymenella very similar to type species in having elongate sub-triangular anterior area, but differing from this and other species in having less strongly developed lateral, preglabellar and occipital furrows. Glabella is of a rounded pentagonal form. Posterior part of pygidial axis is ill-defined. HOLOTYPE. Itl9812. Cranidium. Material. Cranidia: Itl9802, Itl9812, Itl9821, Itl9834, Itl9844. Pygidia: Itl9815, Itl9817. Free cheeks: Itl9803, Itl9826, Itl9832, Itl9837, Itl9855. Locality & occurrence . Cutting on A5 at Caerhun, with a single specimen (Itl9844) from the foreshore at Bangor. Name. From close similarity to type species but occurring much earlier. Description. Cranidium. Three well-preserved specimens known, all about 15 mm long. Poorly preserved specimens are difficult to distinguish reliably from the Neseuretus in the fauna. Cranidium strongly triangular, with slightly truncated, rounded anterior. Glabella occupies approximately three- fifths of preoccipital length (sag.) of cranidium and has rounded, sub-pentagonal outline. At least two pairs of shallow and broad, indistinctly developed lateral furrows are present, with IP lobe moderately well defined. IP furrow inclined gently backwards, causing IP lobe to narrow adaxially. IP furrow also slightly curved, being approximately per- pendicular to axis at inner termination. Axial unfurrowed area present, of approximately same width as shallower portion of occipital furrow. 2P furrow very poorly defined and little more than a shallow depressed area, the orientation of which is unclear, but appears to be elongate pe
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