78 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
but it shows very little or no signs of active or rapid wearing of the 
rocks, 
The surf that breaks against the outer face of the reef is heavy, for it 
comes in from an open and deep ocean where there are no coral reefs to 
break its full force. The depth of 44 fathoms marked on the hydro- 
graphic charts outside comes close up to the reef along most of its 
length. It is remarkable that this violent surf has not affected the reef 
more than it has. There are but few blocks tossed upon the top of it ; 
one of these, however, weighing more than forty-eight short tons, has 
been hurled almost the entire width of the reef, and now rests within a 
few metres of its inner margin. 
Mention should here Бе made of the possible relations of the Cape 
Santo Agostinho reef to a small coral reef just off Cúpe Point. The 
stone reef is in line with the beach to the south for half a kilometre; the 
beach then swings eastward to and around Cúpe Point. East of this 
point a coral reef about six hundred metres long lies a few hundred 
metres off shore. Now the Cape Santo Agostinho reef, like the others, 
has a gentle seaward dip. If this reef continues southward to and 
passes beneath the sands west of Ctipe, its dip must carry it beneath 
the coral reef that lies east of that point. (See map of Cape Santo 
Agostinho reef, p. 71.) 
The beach rocks at Porto de Gallinhas. — Porto de Gallinhas is a little 
village on the coast fifteen kilometres south of Cape Santo Agostinho, 
It is on a sandy flat with fresh-water marshes between the village and 
the hills just west of it. 
There are some rocks of recent origin at this place which, on account 
of their possible relations to the coral reef off the coast, are worthy of 
mention. These rocks are like the ordinary reef rocks, except that 
Fra, 48. Section showing the relation of coral reef to beach sandstone at 
Porto de Gallinhas. 
they contain rather more than the usual amount of calcareous Algae 
fragments. They are exposed when the tide is out at the large ware- 
house that stands on the edge of the beach near the anchorage. Again, 
south of the village, at the first westward turn of the beach, soft cal- 
careous sandstones are exposed on shore by the recent encroachment 
of the sea, These beds have the usual seaward dip, which, if it con- 
