What is "ptychitidae"

The Ptychitidae is a family of ceratitid ammonites (ammonites sensu lato). They are combined with the Eosagenitidae and Sturiidae in the superfamily Ptychitaceae.

Ptychitid genera have compressed, involute shells in which the inner whorls are covered by the outermost, that may be ribbed or smooth, and ammonitic sutures with secondary elelments.