"The Pelecanus Sula, and Sterna stolida, are the only species inhabiting these rocks, together with a fierce and active crab, which appears to be a destructive enemy to their eggs.
"Not a vestige of vegetation of any kind is to be found, excepting a solitary species of Conferva, scantily distributed on the rocks, near the surface of the sea, and with which the noddies and boobies build their nests.
"The hornstone rests upon a very singular-looking rock, of a white colour, and meagre earthy feel; adhering slightly to the tongue, resembling kaolin, or decomposed felspar, beautifully streaked with thin veins of what appears to be serpentine, hard and vitreous as glassy felspar.
"These are the two prevailing rocks, occurring in various states of decomposition; where they are exposed to the spray of the sea, in many places much honey-combed, and intersected by masses of conglomerate, and very curious veins, from half an inch to half a foot in diameter, formed of two thin black plates of rock, much hardened and brittle, with a ringing sound, bearing all the marks of having been subjected to intense heat: frequently the space between the plates, or sides of the veins, is filled by a deposit of carbonate of lime; in others, by a calcareous-looking substance, which does not effervesce with acids, while some are empty.
"At low water, the sea-face of the rocks presents a band of pale red, the work of the coral insects,