liifj a separate opening, whence these shells are calledl 

 foraminifera. Two species are found in the sand of' 

 Flat Island, one nearly globular and smooth being the 

 more abundant ; the other species nearly discord and 

 presenting a number of spines. The foraminifera are 

 now extinct in the European and Northern seas, but 

 AVere abundant in those seas at the epoch of the chalk 

 formation. A few ordinary sea-shells are also found 

 especially at some depth in the sand ; together with 

 considerable numbers of a land shell Caracolla Listeria 

 some of which were imbedded in the cumbling sand- 

 stone already described at a depth of twelve to fifteen 

 feet. The whole surface of the island is more or less 

 strewed Avith this common land-shell, which still in- 

 habits the Cocoas and Vacoas on this island. 



The hard sand-stone rock forms shallow layers or 

 strata on several parts of the coast of the island, and 

 diflfers considerably in its composition at different 

 points. On the western side at Palissade Bay these 

 strata extend from the base of the mountain to the 

 jetty. This sand-stone is composed of foraminife- 

 rous shells, minute fragments of ordinary sea-shells, 

 spines of Echinodermus and water Avorn fragments of 

 coral of all magnitudes, derived from a bed of coral 

 which occupies the entire bay. A narroAV strip of loose 

 sand extends northAvard from the jetty composed of 

 the same materials. This sandstone is in continual 

 process of formation by the aggregation and agglutina- 

 tion of sand washed up by the tide. Mr Mann inform- 

 ed that the holes excavated in the sandstone under his 

 .superintendance for the piers of the jetty Avere imme- 

 diately filled AA'ith sand, Avhich after a very short time 

 was converted into solid sandstone. The material by 

 which the agglutination is effected is carbonate of lime 

 deposited from the sea-Avater, Avhich forms a thin but 

 visible layer around each particle of the sand. 



This sandstone differs in composition to some ex- 

 tent. On the Avest coast of the island at Palissade 

 Bay it is composed of debris of ordinary sea-shells, with 

 the foraminifera, fragments of species of Echini and 

 much fragments of coral, interspersed with larger 

 masses, the Avhole united into a firm stone capable of 



