62 bulletin: museum of comparative zoology. 



low flat country. At Olinda, about five kilometres north of the city of 

 Recife, the high lauds reach the sea. The high hills swing inland from 

 this place to Caxanga and approach the coast again near the town of 

 Cabo, north of Cape Santo Agostinho. The flat country west of Per- 

 nambuco is a recent deposit, and a comparison of maps made during the 

 Dutch occupancy during the first half of the seventeenth century (1630- 

 1644) with the present features shows that the filling up of the old 

 marshes and estuaries is still going on. Two streams, the Beberibe and 

 the Capibaribe, flow across these low lands and enter the sea in the I'ear 

 of the stone reef. These streams are not lai'ge enough for navigation 

 except by canoes and other small boats. The tide ascends the Capibaribe 

 twelve kilometres. From the high land at Olinda a sand spit extends 

 southward, forming the shore and separating the ocean and Eio Beberibe 

 for a distance of four and a half kilometres, to the mouth of the Capibaribe. 

 The city of Recife stands on the southern end of this spit. 



The channel between the Recife spit and the sandstone reef is two 

 hundred metres wide in its narrowest part, while further south it 

 branches to a width of nearly one kilometre. The narrow channel 

 between the lighthouse and the mouth of the Capibaribe is deepest and 

 forms the harbor of Pernambuco. In the broader portions the channel 

 is considerably shallower. Five kilometres south of the lighthouse that 

 stands on the north end of the reef the mainland at the Ilha do 

 Nogueira is only three hundred metres from the reef. The reef from 

 its northern to its southern end, a distance of six kilometres, is very 

 nearly straight, and is unbroken save at one point, the barreta, where 

 there is an opening wide enough to permit the passage of jangadas and 

 such small crafts. At the north end of the reef it seems to be con- 

 tinued in the same direction by a submerged reef about six hundred 

 metres long. Beyond this its course is not distinctly traceable by 

 shoals. At the southern end the reef breaks down gradually, and its 

 southward extension is only suggested by a few submerged isolated 

 breakers lying in the axis of the main reef. There is no apparent 

 difference between the appearance of the reef to-day and its appear- 

 ance during the Dutch occupancy, as shown by the old prints made 

 in 1645. 



Seen from the sea the reef looks like a long, low, artificial breakwater 

 of even surface and with a straight but ragged outer margin. This outer 

 surface is overgrown with corallines and other seaweeds, Serpulae, polyps, 

 barnacles, etc., and is also bored into by sea-urchins. At low tide it is 

 exposed its whole length like a low black wall. 



