317 
tenham, and consists exclusively of detritus from the oolites and lias 
of the vicinity. No bones or terrestrial remains have been found in 
it; and, therefore, the author assigns to it, in the absence of other 
evidence, a marine origin. 
Modern alluvia.—The only deposits of this nature mentioned in 
the paper, are the peaty accumulations on the banks of the Avon 
and its tributaries. 
The memoir was accompanied by a copy of the Railway Section, 
and of the Tewkesbury branch, and the junction branch from the 
main line to the London and Birmingham Railway, presented by 
Capt. Moorsom, but coloured geologically by Mr. Strickland. 
3. A letter addressed to Mr. Murchison by Capt. loyal dated 
London, May 11th, 1840. 
Having read in the instructions prepared by the Royal Society for 
the Antarctic Expedition under Capt. James Ross, that the island of 
Bourbon presents indications of the sea having formerly occupied a 
higher level than at present, and having observed similar appear- 
ances in the Mauritius, Capt. Lloyd was induced to lay the follow- 
ing facts before the Society. 
The island of Mauritius is belted by an enormous coral reef 
throughout its whole circumference, except for about ten miles of 
the broadest and extreme southern side, or from Point Souffleur to 
Souillac, commonly called Port Savanne. Along that part of the 
island the coast is bold, and consists of a basaltic rock. 
Near the Riviere des Galets, between Savanne and the Baie du 
Cap, the sea foams against a barrier of coral from five to fifteen feet 
in height, and wears it into the most fantastic shapes. At a con- 
siderable distance inland, and almost concealed by trees and shrubs, 
are two remarkable points or headlands of coral, from twenty to 
twenty-five feet above the present level of the sea. ‘They present 
the same marks of abrasion as the barrier reef now undergoing 
the action of the waves. The Observatory, Port Louis, is built also 
on a stratum, ten feet above high-water mark, of very hard coral, 
which requires blasting. There are besides in several parts of the 
island, and at considerable distances inland, enormous blocks of 
coral surrounded with the debris of oyster and other shells and broken 
corals. Appended to Capt. Lloyd’s communication are two letters 
from agents employed by him to collect information respecting in- 
land blocks of coral. One of the letters is from Mr. Hill, surveyor 
of roads, and contains the following data respecting two blocks near 
Souillac :— 
Ist Block. 2nd Block. 
Wistancetroms thelsea yuh Na. ena 0 610 feet .... 1856 feet 
Probable height above high water 50 —~ 
Tomer itert eye ai aik ciistiyes a Salad ula wtane My hep sieye ny OO) tae 
read blia saya Aiea? ala eae LOR Ee. Secs) LZ — 
1 SIGUE Teh Ail, SU at ace ake ING, Poth WA 
Girt round the largest projections.. 40 — ..... 77 — 
If the first of these blocks had been transported ‘by the sea, Capt. 
