Wikipedia
Beyrichites
Beyrichites is an extinct genus in the ammonoids cephalopod, order Ceratitida from the Lower and Middle Triassic of southern Europe, Asia, and western North America.
Beyrichites has an involute, discoidal shell with a narrowly arched venter and signoidal ribbing that tends to disappear on the outer whorl. The suture is subammonitic, meaning the saddles are serrate as well as the lobs.
Two subgenera are recognized: B. (Beyrichites) from the Lower and Middle Triassic, which has no tubercles, and B. (Gangadharites) from the Middle Triassic of the Himalaya which has tbercles on the whorl sides.