Marine tuffs interbedded with andesitic lavas and unconformably overlain by lower Miocene limestone on Saipan, Mariana islands, contain a foraminiferal assemblage which is provisionally correlated with the fauna of the Globigerinatella insueta zone, considered late Oligocene in age, in the Caribbean region. The suggested correlation, together with evidence of Miocene volcanism on Yap, implies that volcanic activity in the eastern Philippine Sea was not confined to the Eocene and Quaternary but was recurrent throughout Cenozoic time. Descriptions of Globigerinoides subquadrata n.sp. (by Paul Broennimann) and G. bispherica n.sp. are appended.