(Riedel and Sanfilippo, 1970, emend. 1978a)
The top of the zone is defined by the evolutionary transition from Stichocorys delmontensis to S. peregrina and is coincident with the lower limit of the Stichocorys peregrina Zone.
Events included in the zone are:
- Bm Solenosphaera omnitubus omnitubus; Bm Solenosphaera omnitubus procera
- The lower limit of the zone is approximately synchronous with Didymocyrtis antepenultima -> Didymocyrtis penultima.
The base of the zone is defined by the morphotypic last appearance of Diartus hughesi and is coincident with the upper limit of the Didymocyrtis antepenultima Zone.
Reference slides R 10.1, R 10.2 and R 10.3 from Sample 85-573-14-3, 65-66 cm; R 11.1, R 11.2 and R 11.3 from Sample 85-573-15-CC.