544 Brazilian Corals and Coral Reefs. (September, 
way, but it affords a good base for corals to grow upon, and the 
ebbing and flooding of the tides produce about it a constant cur- 
rent of the purest sea water. No locality could be more favor- 
' able for marine life. As we approach in our canoe, the first 
objects that appear are the millepores, sending upward from their 
shapeless bases the most irregular and fanciful forms, generally 
in the shape of broad leaves or of ramifying branches ending in 
finger points. So wild and luxuriant is their growth at times that 
they partly cover up and obscure the lower-lying heads of more 
solid corals. But scattered everywhere between them, and over 
the edges of the ledge, are huge heads of Orbicella, Acanthas- 
trea and Siderastrea, while Mussas and Porites also occur. 
Other of the shore corals are there too, but from their small size 
escape our notice in this hasty examination. We see only those 
larger forms that stand prominently forward, and thus proclaim 
their great importance in the building of durable structures that 
may last for all eternity. 
This little group of corals, surmounting the rocky ledge, forms 
a miniature reef; it has only to build upward as far as the water 
will allow, and fill in the open spaces either with additional 
growths or with hardened coral sands to possess a true reef struc- 
ture. Now prolong the ledge with its living top; let it stretch 
away for several miles and be broadened out to as many yards, 
and we have a reef such as occurs at times on the Brazilian coast. 
Unless the coast is sinking the reef soon attains its height and 
ceases to grow on top, but it may still continue to increase in 
width. Several of the Brazilian reefs are exactly of this charac- 
ter, having very little height, but from the surface looking like 
very massive structures. A broad area, presenting favorable con- 
ditions for growth, sometimes results in the formation of a wide 
and irregular coral bank, but such are not common near the 
shore. 
We might now enter into a discussion of the many fringing 
and other reefs that lie along the coast; but they are all more or 
less repetitions of one another, are ened in similar ways, and 
composed of the same corals we have been describing. They are 
very many in number, occurring in all favorable localities, espe- 
cially on the coast of Bahia, south of the capital. There is one 
reef, however, that derives a special interest from the accurate 
= of it we are able to give, and having been partially raised 
