A new arthropod from the Silurian Konservat-Lagerstatte of Herefordshire, UK

A small, non-biomineralized, macrophagous arthropod with chelicerate affini ties, Offacolus kingi gen. et sp. nov., from the Silurian (Wenlock Series) of Herefordshire, UK, is described. The dorsal exoskeleton comprises an arc h-like cephalic shield, a thorax of three free tergites and a triangular po sterior tagma of five fused tergites, the last with a stout postero-dorsall y directed medial spine. Seven pairs of appendages beneath the cephalic shi eld surround a postero-medially sited oral cavity on the ventral surface of the head. Appendages I and, probably, II are uniramous and project antero- ventrally; I was sensory and II sensory and/or ambulatory: Appendages III-V I are biramous, each with an antero-ventrally projecting ramus and a robust , highly geniculate, horizontally oriented ramus that projects through an a nterior gape. The former rami were ambulatory and the latter have spinose t erminal podomeres and functioned as a unit for trapping food and transferri ng it towards the oral cavity Appendage VII, which is probably uniramous, i s posteroventrally directed and flap like. Each tergite of the thorax and p osterior tagma covers at least a pair (probably two pairs) of probably bira mous appendages with each ramus flap like and setose.