234 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
matter formed by lime-secreting animals of different kinds is here 
harder than it is near the upper end of the reef, though one may 
sometimes break through and sink to his armpits, or even over his head 
without touching bottom. It is here that the course of the barrier is 
more broken into zigzags. 
The Barreta da Onga, about the middle of the reef, is ten or fifteen 
metres in width, and allows the heavy swell from the ocean to pass 
through. This entrance is deep, and along its bottom grow several 
large Millepores, which could not be collected on account of the depth 
and roughness of the water. Near the south end, and on the inside of 
the reef, there are a few pools containing a number of corals of different 
kinds. No Mussas were found on any part of the Parahyba reef. 
With the exception of the absence of Mussa harttii and the presence of 
Eunicea sulphurea, the fauna of this reef seems to be about the same ав 
that of Maria Farinha on the Pernambuco coast. The marked absence 
of living corals from the northern part of the reef is probably due to 
some extent to the fact that they have been and still are taken out by 
the inhabitants living in the neighboring villages for the purpose of 
making lime. This burning of the corals for lime must be a very old 
custom, and the amount of coral rock thus used must have been at 
times very great. The Fortaleza da Barra at the mouth of the river, 
built in 1712 on the Ponta da Balea, has pieces of imperfectly calcined 
coral in the mortar, and it is plastered in places with lime made from the 
corals of this convenient reef. The city of Parahyba gets its supply of 
lime from the same source, and the burning is still carried on. The 
result is that there are no large coral heads to be found much short of 
the southern extremity of the reef. Here, however, are some very rich 
pools a hundred metres or so within the barrier edge of the reef filled 
with Eunicea, Porites, Favia, Plexaurella, and Millepora. The part of 
reef facing the waves of the open sea also abounds in corallines, sea- 
weeds, crustaceans, etc., and the cavernous calcareous pieces below look 
like fairy grottos as the retreating waves leave the Bryozoa and delicate 
Algae dripping with water. The channel between the coral reef and the 
land admits of barcagas, which may pass in and out at the Barreta do 
Pogo. At low tide, however, only the smallest barcagas can pass readily. 
At this last-mentioned barreta the end of the northern reef lies outside 
of the northern end of the reef to the south, and the ocean current 
brings in through this little opening large quantities of seaweed which 
pile up on the south side of one or two of the curaes! nearest the 
1 Cural is the name given the fish-traps made of poles driven into the mud or 
sand at the bottom of the water. The plural is curaes. 
