(**Footnote.  Captain King informs me that the soundings in this part of the coast bring up a very fine quartzose-sand like that cemented in the breccia.)

ROTTNEST ISLAND, about four hundred and fifty miles south of Dirk Hartog’s Island.  Indistinct specimens containing numerous fragments of shells, in a calcareous cement; the substance of these shells has at first sight the appearance of chalcedony, and is harder than ordinary carbonate of lime.

The characters of the shells in Captain King’s specimens from this place are indistinct; but the specimens at the Jardin du Roi, which, there is reason to suppose, have come from this part of the coast, contain shells of several species, belonging among others to the genera, corbula, chama, cardium, porcellanea, turbo, cerithium.  M. Prevost, to whom I am indebted for this account, observes that notwithstanding the recent appearance of the shells, the beds which contain them are stated to occur at a considerable height above the sea:  and he remarks that the aspect of the rock is very like that of the shelly deposits of St. Hospice, near Nice.

KING GEORGE’S SOUND, on the south coast, east of south from Cape Leeuwin.  Beautifully white and fine quartzose sand, from the sea-beach.  Yellowish grey granite, from Bald-head.  Two varieties of a calcareous rock, of the same nature with that of Dirk Hartog’s Island; consisting of particles of translucent quartzose sand, united by a cement of yellowish or cream-coloured carbonate of lime, which has a flat conchoidal and splintery fracture, and is so hard as to yield with difficulty to the knife.  In this compound, there are not any distinct angular fragments, as in the stone of Dirk Hartog’s Islands; but the calcareous matter is very unequally diffused.

A third form in which this recent calcareous matter appears, is that of irregular, somewhat tortuous, stem-like bodies, with a rugged sandy surface, and from half an inch to an inch in diameter; the cross fracture of which shows that they are composed of sand, cemented by carbonate of lime, either uniformly mixed throughout, or forming a crust around calcareous matter of a spongy texture; in which latter case they have some resemblance to the trunks or roots of trees.  A mass, which seems to have been of this description, is stated to have come from a height of about two hundred and fifty feet above the sea, at Bald-head, on the South Coast of Australia.  These specimens, however, do not really exhibit any traces of organic structure; and so nearly resemble the irregular stalactitical concretions produced by the passage of calcareous or ferruginous solutions through sand* that they are probably of the same origin; indeed the central cavity of the stalactite still remains open in some of the specimens of this kind from Sweer’s Island in the Gulf of Carpentaria.  The specimens from Madeira, presented to the Geological Society by Mr. Bowdich, and described in his notes on that island,** appear upon examination