CIRCUMOCULAR SUTURE AND VISUAL SURFACE OF CEDARIA-WOOSTERI (TRILOBITA, LATE CAMBRIAN) FROM THE EAU-CLAIRE FORMATION, WISCONSIN

Rare specimens of the Late Cambrian primitive libristomate trilobite ' 'Cedaria'' woosteri from the Eau Claire Formation of north-central Wis consin preserve an unusual and new ocular suture, and the impressions of lens facets. The suture is circumocular, but loops abaxially onto t he ocular platform. The portion of the ocular platform that is enclose d by this suture and is fused with the visual surface is here termed t he ''ocular plate''. The size and arrangement of the lens facets show that ''C.'' woosteri possessed a holochroal eye, typical of that known in other Cambrian libristomate trilobites. This nearshore assemblage, while low in diversity, contains a disparate array of trilobite morph otypes.