102 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



Tertiary (?) pebbles embodied iu it. The surface is partly flat and 

 partly etched and rounded. 



The Eio Maracahype enters the sea twenty-three kilometres soiith of 

 the Cape Santo Agostinho lighthouse. Up this stream half a kilometre 

 above its mouth sandstone like that of the stone reefs is exposed at low 

 tide on the north side. It contains many fragments of calcareous Algae. 



South of the Rio da Cruz and between it and the Ponta do Sao Jose 

 there are many exposures of soft calcai'eous sandstone on the beach. It 

 contains many coral fragments and broken calcareous Algae. 



On the beach south of Sao Jose point there is much of this partly 

 hardened rock containing many shells. 



Four hundred metres upstream from the mouth of the Rio Maragogy 

 (S. lat. 9° 3') on its south side, and about sixty metres from the base of 

 the Tertiary (?) hills to the west, is a soft sandstone containing recent 

 shells. 



Rio Salgado, the next small stream south of the Maragogy, has a 

 small reef of soft sandstone across its mouth. It is a rather patchy one, 

 however, and is from one hundred to one hundred and fifty metres out 

 from the beach. Part of this reef lies on the point just north of and 

 opposite Sao Bento. These reef patches are here covered with Serpulae, 

 barnacles, and oysters. Similar rock is exposed withiu the mouth of the 

 Rio Salgado. This looks as if it extended under the plain on which Sao 

 Bento stands. It contains marine shells. 



One and a half kilometres south of the Barreii'a do Boqueirao (S. lat. 

 9° 9') low tide exposes a sandstone reef. It bears iS'. 36° E. (magnetic) 

 and dips gently seaward. The end examined on shore is only one of the 

 fragments of this reef; other fragments lie in a line more than halfway 

 across the erabayment. 



Between Sao Miguel and Rio Camarigibe (S. lat. 9° 19') at a place 

 called Marceneiro the tides have undercut the bank and exposed soft 

 calcareous sandstones from one to two metres thick. The rock is so pure 

 that it is burned for lime. South of Marceneiro this bank of soft calca- 

 reous sandstone continues to have a height of from one to 2.5 metres. 



At Riacho Doce and between that place and Gar9a Torta in the State 

 of Alagoas are several fragments of stone reefs exposed on the beach. 

 At one place there are blocks from thi*ee to eight metres long and a 

 metre thick lying on top of a coral reef and granite boulders. At an- 

 other place a sandstone reef sixty metres long rests on a coral reef, and 

 at still another there is an exposure of one hundred metres of the sand 

 reef alone. 



