DISTRIBUTION OF REEFS. 145 
It will be observed that this agent, so ineffectual on small islands, is one 
of vast influence upon larger lands. Ceylon has some fringing reefs. 
The islands of the Indian Ocean are, to a great extent, purely 
of coral. Of this character are the Laccadives, Maldives, Keelings, 
Saya-de-Malha, Almirante, and Cosmoledo. ‘The Chagos shoal is of 
the same character: and the shoal Cargados is probably similar. The 
Seychelles are small islands with extensive reefs. We remark here 
the same fact alluded to above, that reefs abound in the open ocean, 
though absent from the Continental coasts ; and the same reason may 
apply to both cases. 
Madagascar has a fringing reef upon its southwestern point, accord- 
ing to Mr. Darwin, and on some parts of the coast above; also on the 
north and eastern shores as far down as latitude 18° S.* The Comoro 
Islands, between Madagascar and the continent, have large barrier 
reefs. 
The eastern coast of Africa has narrow reefs extending north with 
some interruptions from Mozambique, in latitude 16° S., to a short 
distance from the equator. Corals also abound in the Red Sea, oc- 
curring in some parts on both shores, though most frequent on the 
eastern, from Tor, in the Gulf of Suez, to Konfodah. This long Con- 
tinental reef may at first be deemed a little remarkable, after what we 
have remarked upon such reefs elsewhere. Yet the surprise is at 
once set aside by the striking fact that this whole coast, from the 
isthmus of Suez south, has no rivers, excepting some inconsiderable 
streamlets. It affords, therefore, an interesting elucidation of the sub- 
ject under consideration, and confirms the view taken to account for 
the absence of reefs from the China and South Asiatic coasts. It is a 
fact almost universal, that where there are large fresh-water streams, 
there are earthy or sandy shores ; and where there are no such streams, 
rocky shores, though not uniformly occurring, are common. 
Passing from the Indian to the Atlantic Ocean, we find little or no 
coral on the west coast of Africa. The islands of Cape St. Anne and 
Sherboro, south of Sierra-Leone, are described as coral by Captain 
Owen, R. N.t But this has been since denied. The island of 
Ascension, in 7° 56’ S. and 14° 16’ W., must have been formerly 
bordered by growing coral, as Quoy and Gaymard mention that a bed 
of coral rock may be seen buried beneath streams of lava. Quoy also 
states that the corals which formed these reefs are no longer found 
* Darwin, op. cit., p. 187. Tt Journal of the Royal Geographical Society, ii. 89. 
37 
