Debranchiate

If this is the significance of septa in the nautilus, the same must be said of all nautiloid shells, and the families of Ammonites and Orthoceratites; and as the structure of the phragmacone of Belemnites is essentially similar, it must also be applied to such debranchiate shells as are chambered.

One was wholly debranchiate, the other had but one gill plume remaining.

Sectioned buccal masses of several debranchiate cephalopods prepared by Mrs. von Boletzky were studied with the help of S. von Boletzky at the Laboratoire Arago in Banyuls-sur-Mer.