Discoceras

Discoceras, a member of the Trocholitidae in the Tarphycerida, not to be confused with Discosorus.

Discoceras is characterized by closely coiled, gradually expanding shells with a subquadrate cross section, that may be ribbed or smooth. The sides are broadly rounded; the venter wide and slightly rounded. The maximum width is slightly dorsal of the middle. The dorsum has a slight to moderate impression. The siphuncle starts off central for the first half whorl then becomes marginodorsal in the succeeding 1.5 to 2 whorls, then subdorsal at maturity. As with Trocholites the dorsal siphuncle in Discoceras probably indicates an orientation during life that places the back of the living chamber high in the shell.