Mr Snell, The Natural History of the Island of Rodrigues 283 



The Natural History of the Island of Rodrigues. By H. J. Snell 

 (Eastern Telegraph Company) and W. H. T, Tams^. (Communi- 

 cated by Professor Stanley Gardiner.) 



[Read 10 November 1919.] 



Rodrigues lies some 350 miles east of Mauritius, and is a rugged 

 mass of volcanic rock closely resembling Mauritius and Reunion. 

 It is surrounded by a coral reef, the edge of which at the eastern 

 end is within 100 yards of the beach, whilst on the north and south 

 it extends outwards to a distance of three to four miles, and on the 

 west to two miles. There is an irregular channel inside the reef 

 close to the shore, extending round most of the island, sufficiently 

 deep for boats at any state of the tide, and at the south-east end 

 a small lagoon of three to ten fathoms, with a passage through 

 the reef. The usual anchorage is Mathurin Bay, in the reef to the 

 north. The reef is studied with islets, those nearer the shore being 

 mostly of volcanic nature, and situated on the north and west, 

 whilst the rest are of limestone, modern accumulations of debris, 

 and situated on the south. 



The island itself is eleven miles long by five miles broad, and 

 has an area of just over forty square miles. There is a central 

 lofty ridge extending from east to west, with a break about one- 

 third of its length from the west. The western bastion of the range 

 is Mount Quatre- Vents, 1120 feet high, while at the eastern end 

 is Grande Montaigne, 1140 feet. The highest point is Mount 

 Limon (1300 feet), which lies with two other peaks a little out of 

 the general line of mountains. The sides of these peaks are cut 

 into numerous ravines, these being deeper and more frequent on 

 the south side than on the north. At their upper ends these ravines 

 are often bordered by perpendicular columnar basaltic cliffs, 

 sometimes exceeding 200 feet in height, extensively cut into many 

 coulees by small streams which often descend in a series of cascades. 



The volcanic ridge descends on the south-west gradually, and 

 passes into a broad coralHne limestone plain, with occasional hills 

 up to 500 feet high, indicating a comparatively recent elevation 

 of at least a like amount. This tract of limestone is honeycombed 

 with caves, in which stalactites and stalagmites are abundant. 

 There are many holes and fissures, and often deep hollows occur, 

 at the bottom of which lie large fragments of limestone in irregular 

 heaps; these are apparently old caves, the roofs of which have 

 fallen in. The floors of these hollows are covered with soil, often 



1 The second author is solely responsible for the names of the insects herein 

 recorded. 



