Ammonoceratites

Ammonoceratites is an extinct genus of ammonoid cephalopod known from the Albian (upper Lower Cretaceous) of British Columbia, Madagascar, New Zealand, and Japan, included in the Lytoceratidae.
The shell of "Ammonoceratites" is evolute, smooth, moderately expanded; the inner rim (dorsum) only slightly impressed; whorl section subcircular. It is similar to that of "Lytoceras" which has transverse ribbing and to that of "Pictetia" which is gyroconic (whorls not touching) and more strongly expanded.