The main interest in boring bivalves has been the method of penetrating the substratum. Mclntosh (1908: 55) listed even "resin, wax and granite" as affected habitats. Boring bivalves have evolved within a number of superfamilies (Kühnelt, 1930, 1933, 1942;Pojeta & Palmer, 1976). Although some investigators, e.g. Hancock (1S48), Lamy (1921), have tried to explain the occurrence of boring bivalves in all observed habitats by only a single theory, they are divided into two main groups: one using mechanical, and the other using chemical means as the agent of boring. Chemical borers are restricted to calcareous marine substrata. Suitable habitats include solid rock and stones of different limestones including dolomite (Kleemann, 1973a). Sometimes it is sufficient that only one component of the substratum is calcareous, e.g. the matrix in certain sandstones (Turner & Boss, 1962: 84\. The shells of a variety of molluscs are also used as a domicile by boring bivalves, e.g. Lithophaga aristato (Dillwyn, l8l7) in chitons (Bullock & Boss, l97l). The skeletons of dead, and surprisingly enough also live corals, get infested, but in each case only by certain species. While most boring bivalves inhabit dead substrata, including dead parts of coral, very few have the ability to penetrate live coral, and these are restricted to that habitat. This ability is not only rare within bivalves, but is rare within molluscs as a whole. The only other groups in which this habit is found are coralliophilid gastropods and mytilid bivalves (Soliman, 1969; Hadfield 1976). With the exception of one (probably two) Fungiacava spp. all, as far as is known, belong to the genus Lithophoga.