. Bulletin of the British Museum (Natural History), Geology. 214 R. A. FORTEY & R. M. OWENS. Fig. 79 Stapeleyella abyfrons sp. nov. Upper Arenig, Fennian Stage, Pontyfenni Formation, S. abyfrons Biozone; loc. 38, Pen-y-parc (except e). a, cranidium, x 6, It. 18959; b, small complete specimen, latex cast from external mould showing bacculae, x 3-5, ; c, lower lamella, x 3-5, It. 18961; d, latex cast from holotype, external mould of almost complete axial shield, x 2, It. 18962; e, small cranidium with attached thoracic segments, loc. 26, Regwm, x 8, It. 18963; f, small pygidium, late
. Bulletin of the British Museum (Natural History), Geology. 214 R. A. FORTEY & R. M. OWENS. Fig. 79 Stapeleyella abyfrons sp. nov. Upper Arenig, Fennian Stage, Pontyfenni Formation, S. abyfrons Biozone; loc. 38, Pen-y-parc (except e). a, cranidium, x 6, It. 18959; b, small complete specimen, latex cast from external mould showing bacculae, x 3-5, ; c, lower lamella, x 3-5, It. 18961; d, latex cast from holotype, external mould of almost complete axial shield, x 2, It. 18962; e, small cranidium with attached thoracic segments, loc. 26, Regwm, x 8, It. 18963; f, small pygidium, latex cast from external mould, x 10, BGS Prl765; g, lower lamella, x 6, It. 18964; h, lower lamella, x 6, It. 18965. Name. In reference to lack of ordered Y-shaped interradial ridges. Description. Glabella clavate, with deep IP and 2P furrows, and weak 3P on pseudofrontal lobe. Small occipital pit a short distance behind IP furrow, running into axial furrow close to it. Occipital furrow very shallow medially, occipital ring rather narrow, without spine. Broad, shallow axial furrow narrows and deepens anteriorly in vicinity of pseudofrontal lobe. Promi- nent, small, ovate alar lobe at posterior end of axial furrow. Genal lobes evenly rounded; those and glabella with very fine reticulate sculpture. Fringe narrow, with 16-17 radii, strongly flexed at girder. El_2 complete. e1_2 or e2 only in some interradii, concentrated towards the anterior; a typical distribution is in o, iv, v and ix, but there is considerable variation on this pattern. These give rise to a few irregularly disposed, commonly asymmetrical 'Y'-shaped interradial ridges. In, Ix complete; some pits in In laterally paired, the components of each pair being very close together. Pits near posterolateral corner of fringe irregularly disposed. Pygidium and thorax like those of S. inconstans except that the pygidial border does not broaden so much towards the posterior and the pleural furrows are a little deeper. Remarks. S
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