pericyclidæ

from The Century Dictionary.

• In Hyatt's classification, a family of magnosellarian eurycampylous ammonoid cephalopods having involute shells with ribs on the venter, broad hyponomic sinus, and with the broad inner lateral saddles of the suture-line divided by short lobes into two subequal saddles. The two principal genera are Dimeroceras of the Upper Devonian and Pericyclus of the Carboniferous limestone.