Clymeniida

an order of extinct cephalopod mollusks of the superorder Ammonites; lived in the late Devonian. Clymeniida were distinguished by the position of the siphon in the shell: it was adjacent to the dorsal side, while in most Ammonites it was adjacent to the ventral side. The shell of the Clymeniida varied from 1 to 50 cm in length. There were approximately 30 genera. The Clymeniida are important fossils for research.