It is most generally regarded as belonging to the pelagic Nucleobranchiata and the family Atlantidae, partly allied to the Glass-Shell, Carinaria; but by some few it is thought to be a simple form of Cephalopod. Portion of Orthoceras laterale. Phill. Goniatites crenistra, Phillips. Mountain Limestone. North America, Britain, Germany, etc. a. Lateral view. b.