The Venom Delivery System of Catfishes. (A) Northern madtom (Noturus stigmosus) with dorsal and pectoral fin spines indicated by red arrows. (B) Pectoral girdle of Noturus stigmosus with articulated pectoral fin spines. Abbreviations: ps = pectoral fin spine, cle = cleithrum, cor = coracoid, cor-pp = posterior process of coracoid. (C) Cross section of the pectoral-fin spine of Noturus stigmosus showing the association of venom gland cells with the fin spine. Abbreviations: ps = pectoral spine, vgc = venom gland cells.