Summary: The petrological and structural characteristics of four layered basic masses in Somalia are described. Sr contents of feldspars from three of the masses are similar for comparable An contents; Sr varies between 1000 and 1850 p.p.m. and tends to increase as An decreases from An₆₈ to An₄₈. In feldspars from the other mass Sr also increases with decreasing An content (An₇₄ to An₅₆), but is at a much higher general tenure (1650 to 2350 p.p.m.). It is concluded that the four masses were not all part of the same layered intrusion.