The present work completes the revision of the Early Pleistocene (Calabrian) protobranchs from the shallow water
deposits of Monte Mario and surrounding localities (Rome), present in the Cerulli Irelli collection. Additional material, mostly from the
Bellardi & Sacco collection, was also studied in order to clarify the taxonomic status of some poorly known species described in the early
literature. Three nuculanid genera are dealt with: Saccella Woodring, 1925, Lembulus Risso, 1826, and Jupiteria Bellardi, 1875. The
Plio-Pleistocene species of Saccella have been often confused as a single, notably variable species, usually reported as Nuculana fragilis
(Chemnitz, 1784) or N. commutata (Philippi, 1844). Four species of Saccella occurred in the Mediterranean Plio-Pleistocene: S.
commutata (Philippi, 1844), S. consanguinea (Bellardi, 1875), S. bonellii (Bellardi, 1875) and S. calatabianensis (Seguenza, 1877). Of
these, S. commutata and S. calatabianensis were present in the Early Pleistocene. Other Plio-Pleistocene species of Saccella are expected,
basing on literature data and on available material. Lembulus included a single Plio-Pleistocene and extant species, L. pella (Linné,
1758). Jupiteria occurred in the Plio-Pleistocene with a single shallow water species, J. fissistriata (Foresti, 1897 ex Meneghini ms), but
two other deep-water species are known: J. concava (Bronn, 1831) and J. gibba (Seguenza, 1877). These genera show a general
southward shift in distribution through the Miocene-Pleistocene, which led Saccella and Lembulus to disappear from the North Sea and
Jupiteria from the Mediterranean and adjacent Atlantic.