The Ptychitidae comprises a family of ceratitid

Ceratitida

The Ceratitida is an order that contains almost all ammonoid cephalopod genera from the Triassic as well as ancestral forms from the Upper Permian, the exception being the phylloceratids which gave rise to the great diversity of post Triassic ammonites....

  ammonites (ammonites sensu latu). They are combined currently with the Eosagenitidae and Sturiidae in the superfamily, Ptychitaceae

Ptychitaceae

The Ptychitacheae is a superfamily of typically involute, subglobular to discoidal Ceratitida in which the shell is smooth with lateral folds or strigations, inner whorls are globose, and the suture is commonly ammonitic...

.

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.

References

• Arkell, et al, 1957. Mesozoic Ammonoidea, in the Treatise on Invertebrate Paleontology, Part L . R. C.Moore (ed). Geological Society of America and Univ of Kansas press.
• Ptychitidae-Paleodb
• classification of E.T. Tozer, 1994