Petrosia pulitzerin. sp. (Demospongiae, Petrosiidae) is described from three specimens collected from totally submerged marine caves from the Island of Crete and the Gulf of Naples. They are massive or encrusting, white or yellowish in conditions of reduced light, and stony hard in consistency. They show a skeleton formed by stout tracts of closely packed spicules (mostly strongyles) with a peripheral mesh condensation. The new species is close toPetrosia ficiformis, but shows spicular and skeletal differences.