18709. | Brazilian Corals and Coral Reefs. 551 
very fully described the various Brazilian reefs formed by chapei- 
roes, and there is little new to add; but we will take a hasty 
glance at them in order to complete our sketch. The Abrolhos 
islands lie some forty miles from the coast, near the middle of the 
submerged continental plateau, in about latitude 18° south. Sur- 
rounding them is a very extended area of constantly warm and 
pure water, everywhere less than a hundred feet deep. Just to 
the eastward of these islands is a region, nine or ten miles long 
and about four broad, over which the pillar-shaped structures are 
thickly scattered, forming the well-known Parcel dos Abrolhos. 
The chapeirdes occur here of all heights and sizes, but never 
reach the surface, or coalesce to form a continuous reef. 
To the north-west of the Abrolhos, and reaching much nearer 
to the mainland, is the largest reef region of the Brazilian coast, 
called the Parcel dos Paredes, or Shoal of the Walls. It is irregu- 
lar in outline, being about seventeen miles long from north to 
south, by about nine miles broad in the widest place. Within 
this area are extensive connected reefs, as well as multitudes of 
scattered chapeirdes. The northern part of the Parcel forms one 
immense reef, reaching slightly above the level of low tide and 
formed by the growth of large coral patches and by the coales- 
cing and filling in of chapeirdes. This latter feature in reef 
building has been noticed only on the coast of Brazil. The edges 
of the reef are very irregular, but the upper surface, laid bare at 
low tide, is of quite uniform height, although marked by many 
scattered shallow pools. Running along the margin of this level 
portion, and separating it from that which is constantly submerged, 
is a slightly raised border, a foot or less in height, formed by the 
growth of nullipores, serpula tubes and barnacles. At low water 
the waves beat against this hard rim, which thus helps to protect 
the upper part of the reef from wear. The submerged border of 
the reef dips gently for a certain distance, and then breaks down 
abruptly to a depth of three to ten feet, meeting a bottom of soft, 
bluish, calcareous mud which slopes rapidly away, soon attain- 
ing a depth of seventy to eighty feet. Chapeirdes surround much 
of this large reef, and extending off southward from it, form two 
other reefs, the Recife de Leste and Recife da Pedra Grande, com- 
prising the rest of the Parcel. 
~ Several other reef patches, resulting from the growth of cha- 
_Peirdes, occur between the Abrolhos islands and the mainland, 
and also farther north along the coast of Bahia. 
