Article: The lectotype of the ammonite Cadomites psilacanthus (Wermbter)

The inflated 'Am. humphriesianus' d'Orbigny (1845, pl. 134, figs. 1-4), non J. Sowerby (1825), has subsequently been named three times; the oldest objective synonym is Stephanoceras psilacanthus Wermbter (1891). The lectotype has been found in the British Museum (Natural History) and is redescribed. It probably came from the boundary Humphriesianum-Subfurcatum Zones at Sully, near Bayeux, Normandy. Specimens from the Parkinsoni Zone described under Cadomites arkelli Sturani (1964), the youngest objective synonym, are C. psilacanthus sturanii subsp. nov.