Ss. 
DESCRIPTION OF THE EXPEDITION. 119 
Pits, troughs, and hollows varying up to 6 fathoms in depth occur here and there, but 
they are not generally fringed with corals as are similar pits in the Chagos or Maldives. 
Indeed, corals only grow close to and on the sides of the entrances, while Lithothamnia 
are almost confined to the breaking edges and outer slopes. The inner parts of the reefs 
(or mud-banks, as in this situation they might more properly be termed) are really formed 
largely by detritus from the land of material similar to that which forms Terre Rouge 
mentioned above. So far as we could see here and elsewhere, the determining factor in 
coral-growth appeared to be silt, much dead coral slimy with mud and dirt being found 
in many places. 
From Mahébourg we passed in one day’s sail along the passage to Grand River S.E. 
to the Beauchamp Factory. We sounded in places and examined many points of the 
coast and reefs. There appeared to be no marked changes in progress, but if the strong 
current which we found sweeping out of the north entrance of Grand Port is of general 
occurrence, the amount of water-suspended material cleared away must be very great. 
We found on the coast no further raised limestones, but Coral Point seemed to be 
formed of deposited material similar to that of Terre Rouge. The views into the 
Bamboo Mountains presented scenes of great beauty, and clearly showed in deep ravines 
how long-continued must have been the action of weathering. 
Subsequently we devoted three days to the reefs and coasts near Ile aux Cerfs, Flacq, 
and Ile d Ambre, at each of which there are passages through the reef suitable for small 
vessels. The reefs of all three places are intermediate between barrier and fringing. 
All the islets are purely of volcanic formation, and have been cut off from the mainland 
by the action of the sea. In each place the passages seemed to be the natural outlets of 
the tidal waters. The Riviére Seche has no passage corresponding to its mouth, while 
the Trou d’Eau Douce has no connection with any river. At Flacq the rivers come 
down from the central plateau and are more considerable. Doubtless they carry a 
large amount of material in suspension and the passages through the outer edge of the 
reef partially owe their existence to its prejudical effects. The half-dozen passages near 
Ile d@ Ambre, however, cannot conceivably be connected with any streams, and opposite 
the Riviére du Rempart, a relatively: considerable stream, there is a large lagoon 
within the reef, fringed and studded with corals, the reef-edge there attaining a distance 
of 24 miles from the land. 
In the north of the island we saw no further evidence of elevation. The country 
forms a rich plain densely cultivated with sugar-cane and other products. Its coast is 
ragged, with here and there swamps and pools artificially cut off from the sea to form 
fish-ponds termed “ barachois.” Mangroves, principally Rhizophora, grow everywhere, 
but nowhere in any great profusion; their stilt-like roots are often covered with oysters. 
On the edge of this plain is situated the garden of Pamplemousses, a beautiful pleasaunce 
rather than a botanical station of either scientific or economic value. ‘The real care of 
the government is in the preservation of its forests and in providing such chemical- 
agricultural assistance to the planters as they cannot themselves be reasonably expected 
to provide. The cultivation of the cane is carried to the highest pitch, and great care 
is taken as to the varieties planted on each kind of soil. At Beauchamp, the biggest 
SECOND SERIES.—ZOOLOGY, VOL. XII, 18 
