6?2 A PPF, Nm X. It. latter ease they have ?ome reeemldance to the trunks or root? of tre?.--A mass, which seems to have been of thi? 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 exh?it any traces of organic structure; and so needy resemble the irregular stalacfifical concretions wodueed by the passage of calcareous or ferruginous so- lutions through sand *, that they are prolYably of the same origin; indeed the ceuVral cavity of the. stalactite still mains open in some' of the spedmens of this kind f?rom �SweePs Island in the Oulf of Carpentaria. The specimens from Madeira, presented to the Geological Society by Mr. Bowdich, and described in his notes on that islandt, ap- pear upon examination to be of the same oharaeter.--But there is no reason to suppose that the tru?s of trees, as well as other foreign substances, may not b? thus incrusted, since various foreign bodies? even of artificial production, have been so found, Professor Bucklaud has mentioned specimen of concrete1 limestone from St. Helena, which contains the recent shell of'a blrd's egg**; and M. Ptron states that, in the coneretional limestone rock of the South Coast of I%w Holland, the trunh of trees occur, with the vegetable structure so distinot as to leave no doubt as to their nature i.
- Tubuhu- concretions offerr,g/oaf matter, irregularly ramify-
ing ?hrough sand, like the roots of trees, are described by Captain Lyon as occuring in Africa--Lyon's Travels, Appeudix, p. 65. , Excursions in Madeira, 1825, p. 139, 140; and Bull des flciences Naturelies, vol. iv. p.
- 1: Oeol;"lh'ans. ,01. v. p. 479.
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