The present study deals with the taxonomical consideration of the forty-seven species of planktic foraminiferal Paleogene species belonging to 6 genera from Ja’alan area, south East Sultanate of Oman, Arabian Sea, and represent good example of the Southern Tethyan Paleogene assemblage, which were originally identified by Al-Sayigh, (1998). The Oman assemblage are recognized between the Upper Palaeocene (P4) and upper Middle Eocene (P14). Eight species of the recorded assemblage are believed here to be new: Globigerinatheka arabica, Globigerinatheka omanica, Acarinina umbilicata, Morozovella elbadrii, Morozovella elsayighi, Morozovella omanica, Morozovella surensis and Morozovella wadimusawaensis. A possible hiatus representing the planktonic zones P5/P8 is recognized. The wide paleogeographic distribution of this assemblage in Oman and different localities around the surrounding area and also other Northern and Southern Tethys indicates that the ancestral Tethys is connected with the ancestral Atlantic to Pacific Oceans (via Mediterranean Sea and Indian Ocean). The study section was deposited in an open deep marine environment which represent outer shelf (~200m), and was tectonically active, with marked oscillations in sea level.