Madagascar and New South Wales . 479 
Antrim, and at the falls of Devon, near Kinross in Scotland, occurs 
associated with a similar red sandstone. In the same neighbourhood 
of Port Lougui, and the river Vouluceer, there are found trap 
rocks, which present several varieties of fine-grained greenstone, 
and also specimens of coarse white pipe-clay and of fuller’s earth ; 
the pipe-clay appearing to be derivative from a decomposed granite. 
Besides these rocks, all of which have a strong resemblance to 
formations that occur in Europe, the Island of Madagascar presents 
a variety of that species of modern and daily accumulating limestone, 
which is of frequent occurrence near sea- coasts that are exposed to 
the action of violent seas, being composed of sand and minute 
fragments of ground shells, which being first accumulated on the 
shore, and subsequently drifted inland, are in a short time consoli- 
dated into fixed masses and compact strata. *• 
The specimens of a rock of this formation from Madagascar, exhibit 
a firmly compacted cream-coloured limestone, composed of granu- 
lated fragments of shells, agglutinated by a calcareous cement, but 
too much broken to allow any of their species to be ascertained. 
Limestone of this kind is applicable to most of the ordinary uses 
of that mineral, and is often the only calcareous rock that occurs oh 
volcanic islands. 
There is a curious specimen of such limestone in the library of 
the East India House, which contains imbedded in it a small and 
recent bird’s egg, with the shell unchanged. This specimen is from 
St. Helena; and bones of modern birds are said to abound in the 
same rock, and also to lie loosely scattered over certain parts of its 
surface. This is easily explained by the circumstance of the origin 
of the limestone, from periodical driftings by the wind of calcareous 
sand, over districts frequented, as these are said to be, by innume- 
Vol. V. 3 p 
