Abundant siliceous sponge spicules were found in the lower and middle Eocene sediments of Site 605 and the upper Miocene sediments of Site 604. The assemblages consist mostly of monaxons. Relative abundances of the various types are tabulated. All those from the Miocene sample, and the majority of those from the Eocene sample, belong to the Class Demospongea. A small minority of the Eocene spicules are from the Class Hexactinellida.