62 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
low flat country. At Olinda, about five kilometres north of the city of 
Recife, the high lands 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 а 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 rear 
of the stone reef. These streams are not large 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 Rio 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, ete., and is also bored into by sea-urchins. At low tide it is 
exposed its whole length like a low black wall. 
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