98 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



0-: 



On the brow of this bluff stands the old town or upper city of Porto 

 Seguro. The view from the edge of the plateau is remarkably fine, and 

 throws much light upon the geogi'aphic history of the region. The ac- 

 companying sketch was made from the southwestern edge of the plateau 



in the outskirts of the old town. 

 It was made so late in the day, 

 however, that the details of the 

 hills on the south side of the val- 

 ley could not be seen. South of 

 the valley these same steep-faced 

 hills continue down the coast. 

 The valley of the Rio Cachoeira 

 is flat-bottomed, here sandy and 

 there covered by mangues that 

 extend back and up the smaller 

 channels from the margin of the 



° -§ main stream like fingers from a 



c o 



^ ^ hand. This flat valley, about its 



1 ^ lower end at least, is less than 



2 J one metre above the highest tides. 

 2 3. On the south side of the river is 

 ^ J a caatinga forest where the land 

 ^ "^ is four metres above mean tide 



1 & (Wagoner). 



^ " The Porto Seguro reef has its 



5 ~ southern end joined to the land 



5 and lies square across the mouth 



■i of the valley and of the Cachoeira 



o River, which it deflects northward. 



a; The main unbroken reef is one 



s thousand six hundred metres long, 



but beyond this to the noi'th and 

 S lying in the line of the reef are 



2 four separate pieces which add 

 "^ six hundred metres more to its 



length. It varies in width from one hundred and thirty-five metres near 

 its southern extremity to thirty metres in the narrowest part of the main 

 reef; throughout the greater part of its length it averages thirty-five 

 metres. At high tide the water breaks over it the entire length, but it 

 is more effective as a breakwater than the Pernambuco reef. Its general 



