604 MR. J. J. LISTER ON THE GEOLOGY 



with a large uiiraber of foraminifera " *. True coral does, how- 

 ever, exist on this terrace, as I found one large mass clearly 

 exhibiting a structure like that of a Pontes. 



The limestones from the higher part of the island present for the 

 most part a compact structure. Some of them are crowded with 

 foraminifera, but large masses of coral appear to be absent. 



With regard to the nature of the limestone formations as a whole, 

 as indicated by the sections above described. Dr. Murray writes to 

 me that they " may all have been formed in or about reefs, and 

 true coral-reefs may have been living quite close to them when they 

 were laid down ; " but from the scarcity of examples of the larger 

 corals he concludes that " it is more likely that they were laid down 

 in depths of from 30 to 100 fathoms, and that they formed the base 

 of true coral-reefs." 



The conformation of the surface of terrace a points to its having 

 formed a true reef, and having been elevated without much denu- 

 dation ; but in the case of terrace h and the higher limestone rocks, 

 the extent to which they have evidently been denuded and their 

 nearness to the volcanic basis bear out Dr. Murray's view, founded 

 on the nature of the organisms they contain. 



Some features of interest are presented by the shores of the 

 island. 



On its western side, in the neighbourhood of the village of 

 OMinua, the island is bordered by a narrow fringing reef some 50 

 to 100 yards in width. There are clear traces here of recent eleva- 

 tion. To the south of the village there is a low shore-cliff under- 

 mined by the action of the sea, but separated from the present 

 shore by a strip of sand some 50 to 60 yards wide, covered with 

 cocoanut palms and other trees. 



From a little to the north of the village the island is bordered by 

 a cliff some thirty feet high, which extends to the northern end. 

 The foot o£ this cliff is washed at high tide by the sea, and is deeply 

 undermined, the upper limit reached by the action of the sea being 

 sharply defined. Above this present line of undermining, and sepa- 

 rated from it by a projecting ledge of rock, there is another and 

 older one, the upper limit of which is sharply defined and separated 

 from that of the present line of wave-action by a distance of seven 

 feet. When looking at the cliff from the sea, I thought I detected 

 a third line of wave-action at a still higher level. 



From the foot of the cliff the shore-platform extends some fifty 

 to a hundred yards, and is bordered by growing coral. Over the 

 greater part of its extent this platform is flat, and at high tide is 



* Miliolina, sp. 



Orhitolites com'planata ('?). 

 Textularia trochus (d'Orb.). 

 Folymorphina, sp. 

 Glohigerina (btclloides?). 

 Truncatidina, sp. 

 Pkmorhulina larvata (P. & J.). 

 Carpenteria monticularis (Carter). 



Folytrema miniaceum (Linn.). 

 Gypsina inhcBrens (Schultze). 

 Rotalia, sp. 



Calcarina hispida (Brady). 

 Cycloclypeus Carpenteri (Brady). 

 Heterostegina depressa (d'Orb.). 

 NammuUtes Cumingii (Carpt.). 



