branner: the stone reefs of brazil. 229 



sent by Mr. Sampaio from the vicinity of Cidade do Forte belong to the 

 genus NuUijKjra." ^ 



At a immber of places along the coast of Rio Grande do Xorte the 

 reefs are neither coral nor of the ordinary recent sandstone, but are of 

 the more resisting iron cemented sandstones of the Cretaceous or Ter- 

 tiary series. These beds, as has been pointed out in the geological intro- 

 duction, are often formed at the bases of the bluffs, where, when the 

 overlying beds are removed, they are in the right position to leave reefs 

 close to mean tide level. Such are the reefs off the Pittingui, Cape 

 Branco, Jacuma, etc. Even if the Sao Eoque reefs are all of coral, the 

 chances are that they are built upon some such base as the one here 

 mentioned. 



The absence of coral reefs along the entire coast from Natal, south 

 latitude 5" 45', to the mouth of the Eio Parahyba do Norte, south lati- 

 tude 6° 57', is striking. All the reefs within this space are either sand- 

 stone reefs or hard Cretaceous or Tertiary beds rising to about meau 

 tide level. 



Fernando de Nwonha. — The following notes upon the corals of the 

 Fernando de Noronha archipelago were made during a three months' 

 visit to that island in 1876, when the writer was a member of the 

 Geological Commission of Brazil. They are given here, not on account 

 of their importance, but partly because mention has been made by Mr. 

 H. N. Ridley of the " coral reefs " about the group,- and partly because 

 one might naturally expect to find coral reefs about that group of 

 islands. 



The main island of Fernando is volcanic, and all the outliers around 

 it are of similar origin except Ilha do Meio and Ilha Raza, which are of 

 aeolian sandstone.' Properly speaking there are no coral reefs around 

 Fernando, though growing upon the rocks about the group are a few 

 corals, and still other corals that were not found in place are from time 

 to time torn up from the ocean bottom and thrown upon the beaches 

 by the heavy surf. The following is a list of all the species collected 

 on and about the island. For the identifications I am indebted to Mr. 

 Richard Rathbun, formerly of the Geological Commission of Brazil, now 

 of the Smithsonian Institution. 



1 J. B. von Spix u. C. F. P. von Martins. Reise in Brasilien, II., p. 790. Miinchen, 

 1828. 



■^ Journ. Linn. Soc. Zoology, 1890, XX., p. 550. 



' J. C. Branner. The aeolinn sandstones of Fernando de Noronlia. Anier. 

 Journ. Sci., 1800, XX XIX., p. 247-257. 



