Plectoceras is a nautiloid genus included in the tarphycerid suborder Barrandeocerina that lived during the Middle and Late Ordovician. It has been found widespread in the Middle and Upper Ordovician of North America. Plectoceras has a coiled, costate shell with a perforate (see-through) umblilcus; whorls are dorsally impressed by end of first vol...
Found on
http://en.wikipedia.org/wiki/Plectoceras
extinct genus of small marine nautiloid cephalopods, forms related to the modern pearly nautilus, that had a coiled shell composed of a series of ...
Found on
http://www.britannica.com/eb/a-z/p/79
No exact match found.
