Genus Saffordoceras is an actinoceratid

Actinoceratidae

The Actinoceriatidae is a family of actinocerids named by Saemann in 1853 for those that grew to have large shells with blunt apecies and large siphuncles with widely expanded segments and a generally arcuate endosiphucular canal system. Their range is from the upper Middle Ordovician to the Lower...

 from the Middle Ordovician, found in eastern North America, characterized by a flattened venter; sutures with broad, deep ventral lobes and narrow lateral saddles; and subventral siphuncle with segments decreasing from about 0.3 to less than 0.2 the shell diameter. Saffordoceras is probably derived from Actinoceras

Actinoceras

Actinoceras is the principal and root genus of the Actinoceratidae, a major family in the Actinocerida, that lived during the Middle and Late Ordovician.- Morphology:...

. Related contemporary genera include Paractinoceras and Troostoceras

-References-

• Curt Teichert, 1964. Actinoceratoidea. Treatise on Invertebrate Paleontology, Part K. Geological Soc of America and Univ of Kansas Press.