210 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 
Mr. Hawkshaw was an assistant of Sir John Hawkshaw, who had the 
borings made through the stone reef at Pernambuco in 1874. His paper 
gives the section disclosed by the boring upon the reef opposite the 
marine arsenal. He raises the question whether the existence of a bed of 
hard rock below the reef can be regarded as evidence of an older beach 
consolidated when it was at the surface. He is of the opinion, however, 
that the coast has recently risen. He says the cementing material is 
carbonate of lime, Не is of the opinion that these reefs have been 
formed from long sand ridges with lagoons behind them; that “the 
percolation of land-water charged with carbonic acid derived from the 
decayed vegetable matter in these lagoons through the sand ridges will 
account for the formation of the beach rock, the water taking up and 
again depositing the carbonate of lime of the shells." “The flood-level 
of the lagoon will determine the level of the upper surface of the beach 
rock; and that of the lower surface would be determined by the 
cessation of the consolidating action at the level at which the sand was 
saturated by sea-water.” 
Henderson, James. A history of the [sic] Brazil; comprising its geog- 
raphy, commerce, etc. London, 1821, р. 382. 
In speaking of Pernambuco, it is stated that “A recife, or chain of 
reefs, which extends itself from the entrance of Bahia to Cape St. 
Roque . . . in no part appears so much like an operation of human 
art as here. It is prolonged for the space of a league in a direct line 
with and about two hundred yards from the beach, having the aspect of 
a large flat wall, being always above the level of the sea, and at low 
water six feet is discovered.” It is “ perpendicular on the land side, and 
gradually declining on the other.” 
Hinchcliff, Thomas W. South American sketches; or a visit to Rio 
de Janeiro [sic], the Organ Mountains, La Plata and the Paraná. 
London, 1863. 
On р. 11, he calls Recife “a coral reef, which extends, with few inter- 
ruptions, like a regular sea-wall, for nearly four hundred miles along the 
coast of Brazil.” 
Keller, Franz. The Amazon and Madeira Rivers. New York, 1874. 
This writer, in speaking of Pernambuco, says that: “On the remark- 
able coral reef that protects the port are a fine new lighthouse and a 
quaint old watch-tower. . . . This coral reef . . . is extending all along 
the coast of Brazil” (p. 26). 
