CORALS. 
5 2 5 
the better growth of the corals on the outer edges of the reef which are most 
exposed to the action of the surf, and the sweeping of the coral material out of the 
lagoon through the agency of oceanic currents, and the dissolving action of the 
barrier-reefs from the neighbouring mainland are formed in the same way. The 
enormous magnitude of the reefs which the theory of subsidence demands is 
nowhere realised. Neither among modern reefs nor among geological formations 
do we find any traces of such gigantic masses of coral-rock. We are thus in 
face of a fascinating and important scientific problem, which still remains to 
be solved, a problem which was long thought to have found its solution. After 
Darwin’s and Dana’s subsidence theory had been generally for many years 
accepted as beautiful and completely satisfactory, we are told that it is not 
always applicable, and that much simpler causes suffice to explain the phenomena. 
It is obvious, then, that we have an ample supply of possible explanations of 
coral-reefs, and it is most probable that among the many scattered reefs in the 
world, in one case one set of factors have played the chief part, in another case 
a slightly different set, and further, a detailed and exhaustive study of any 
particular reef would probably reveal natural processes of no small importance 
which have not as yet been taken into account. 
H. AND M. BERNARD. 
MOUTHS OF MADRETORE. 
