Article: Silicified trilobites of the family Asaphidae from the Middle Ordovician of Virginia

Protaspis, meraspis, and holaspis stages of Isotelus giselae sp. nov. from the Edinburg Formation (Middle Ordovician) of Virginia are described; diagnostic features of the dorsal shield are the absence of a distinct lateral depression, and the short, strongly elevated palpebral lobes. Four moults during the protaspis period are denned by changes in the hypostomes. Iotelus spp. A-E, from the lower and upper Lincolnshire, Oranda, and Martinsburg Formations (Middle Ordovician) of Virginia are based on less complete material. Nahannia sp. is described from the Lincolnshire Formation.