Numerous paleontological investigations have been made of different fossil fauna of the Philippines but none has yet included the fossil Radiolaria. This group of fossil micro-organisms can be considered one of the most interesting and valuable aids in micropaleontology. Their planktonic nature, great variety in form and abundance make them good index fossils. They are also important in the interpretation of ecological conditions prevailing at time of deposition. In the absence of Foraminifera and other fossils the Radiolaria can be utilized in the age determination of a rock unit.