Lophoceras is a Nautilid

Nautilida

The Nautilida constitute a large and diverse order of generally coiled nautiloid cephalopods that began in the mid Paleozoic and continues to the present with a single family, the Nautilidae which includes two genera, Nautilus and Allonautilus, with six species...

 genus belonging to the tainoceratacean

Tainocerataceae

The Tainocerataceae is a superfamily in the cephalopod order Nautilida characterized by straight to loosely coiled shells, generally with a degressed, such that the width is greater than the height, to quadrate whorl section. Many bore spines, ribs, frills, wings, or nodes...

 family, Koninckioceratidae

Koninckioceratidae

The Koninckioceratidae comprise a collection of nautilid genera, typically with more or less evolute shells with depressed whorl sections, that are combined as a family within the Tainocerataceae...

, found in Lower Carboniferous sediments in Europe, and named by Hyatt, 1893. The shell of Lophoceras is evolute, large, with a slight impressed zone on the inner rim. In early volutions whorl sections are rounded, but later develop an obtusely angular ventral area and venter that disappears toward the front of the mature body chamber. The suture has an angular ventral saddle, broad shallow lateral lobe, and a dorsal lobe. Except for growth line, the shell is smooth.

References

• Bernhard Kummel, 1964. Nautiloidea-Nautilida. Treatise on Invertebrate Paleontology, Part K. Geological Soc. of America and University of Kansas press. Teichert and Moore (eds)
• Koninckioceratidae-Paleodb