Fig. 3From: Ontogeny and morphology of the retrochoanitic septal necks of Agoniatites vanuxemi from the Middle Devonian Cherry Valley Limestone Agoniatites vanuxemi. Septal–siphuncular membranes. a PRI 68137, second whorl. Scale bar 20 μm. b AMNH 53357, second whorl. Scale bar 20 μm. c, d PRI 68138, second whorl. c Scale bar 100 μm. d Scale bar 100 μm. SSM septal–siphuncular membranes, V ventral surface of chamber, S septum, arrow adoral directionBack to article page