TERRA AUSTRALfS. 
429 
Wilhems Plains.'] 
olivine ; it is more or less ferruginous, gives a bell-like sound when 1806 - 
struck, and in some parts appeared to have run in the manner 0 f September ‘ 
lava. From this description, and the circular form and elevated 
position of this basin, the geologist will probably be induced to think 
it the crater of an ancient volcano ; and since there are other large 
holes nearly similar to it, and mcfny caverns and streams under 
ground in other parts, it may perhaps be concluded that if the island 
do not owe its origin to subterraneous fire, it has yet been subject 
to volcanic eruptions, and that the Grand Bassin was one of the 
vents. 
Such were the rivers, lakes, and views which most excited my 
excursions to the north, the west, and south of the Refuge. To 
the east at a league distance, there was, according to my information, 
a lake called the Mare aux Jones, from whence rises the R. du Menil ; 
and taking its course northward, joins the R. de Wilhems and at 
length falls into the Grande Riviere. At a further distance several 
other streams were said to rise, some running northward to the 
same destination as the above, and others south-eastward towards 
Port Bourbon ; but having never visited this part of my limits, I 
can speak of it only from report, corroborated by a view of the 
chart. The country was represented as less inhabited than Vacouas, 
owing to the want of roads and consequent difficulty of conveyance 
to the town, upon which the value of land very much depends : an 
uncleared habitation * near the Mare aux Jones was sold for 500 
dollars, whilst the same quantity of land at Vacouas was worth six 
times that sum. 
Upon the high land near the Grand Bassin and in some other 
* The original concessions of land in Mauritius were usually of 156f arpents, of 
40,000 French square feet each, making about 160f acres English; this is called un 
terrein d’habitation, and in abridgment a habitation, although no house should be built, 
nor a tree cut down ; by corruption however, the word is also used for any farm or planta- 
tion, though of much smaller extent, 
