Article: The Ordovician trilobite fauna of the Sholeshook Limestone Formation, South Wales

This paper gives a complete account of the historically important trilobite fauna of the Sholeshook Limestone; it comprises 50 species here placed in 40 genera and representing 23 families. Three new species, Harpidella (H.) lacrymosa, Platylichas noctua, and Primaspis llandowrorensis are included. Species of Liocnemis and Whittingtonia occur in laterally equivalent parts of the Slade and Redhill Mudstone Formation; the former genus is described for the first time from British strata. Proceratocephala is described for the first time from Wales. The rostral plate of Stenopareia bowmanni (Salter) is described, and a free cheek figured. A pygidium is described for a form tentatively referred to Panderia edita Bruton. Well-preserved topotype specimens of Pseudosphaerexochus juvenis (Salter) give a better characterization of the species than Sailer's original syntypes. A thorax is illustrated for Duftonia geniculata Ingham, and a distinctive hypostoma is described for a form tentatively referred to Platylichas angulatus Warburg. Ranges and abundances are charted. The Sholeshook Limestone was deposited in an environment intermediate between deep-slope mudstones and shelf-edge carbonates, and has elements of its trilobite fauna in common with both facies types.