Cyclostomiceratidae


Cylostomiceratidae is a family of Early Ordovician,, ellesmerocerid cephalopods characterized by short, essentially straight shells, a fairly rapidly expanding phragmocone and a ventral siphuncle in which septal necks are almost non-existent and connecting rings are thick and layered. As typical of the Ellesmerocerida, chambers are short, septa close spaced.

Genera

Five genera are recognized; Cyclostomiceras, Eocyclostomiceras, Microstomiceras, Paracyclostomiceras, and Pictetoceras. Cyclostomiceras and Paracyclostomiceras were described in Flower.
Microstomiceras and Pictetoceras come from the Middle Ordovician Hälludden cliff section, Oland Island, Sweden, associated with such as Paldoceras.