BY B. SAWYER AND E. C. ANDREWS. 97 



occur throughout its 300 yards of length, and numerous subsidiary 

 caverns ramify from the parent trunk. Other chambers of con- 

 siderable size occur in a cliff to the south. 



2. Tldthia. — This island is almost a replica of Mango in every 

 particular. Its caverns, however, partake more of the nature of 

 lofty halls than long tunnels. Stalactites and stalagmites of great 

 size occur in abundance. Immense deposits of bat guano cover 

 the floors. In one cave a deposit 18 ft. deep was worked. The 

 excessive moisture is said, however, to militate against the ready 

 sale of these manures. 



3. Lakemha. — A large cave occurs in one of the irregularly 

 scattered patches of limestone existent on this island. The 

 cavern is curvilinear in shape, not advancing directly into the 

 hill, but turning back somewhat on itself from the start, so as to 

 give the appearance, in plan, of a horseshoe with reduced con- 

 vexity. It is a magnificent example of cave formation and 

 worthy to rank among occurrences like Jenolan in point of size, 

 though not in beaut}^ The floor, contrary to the usual type, is 

 almost level, very wide, and covered with a thick deposit of mud. 

 It is in the form of two large chambers, each about 300 yards in 

 length, 50 ft. in width, and 50 ft, in height. A row of columns 

 (stalactites) separates the caverns. 



The roof is like that of a church, having a long central ridge, 

 with two steeply inclined sides. Huge grey and white stalactites 

 of irregular shape depend from the roof. 



4. Nghillanghillali. — A marvellously beautiful little cave occurs 

 in one of the islets forming the Nghillanghillah Group. * All of the 

 raised coralline rocks composing the islets possess deep undercut 

 lines of beach erosion. One is about 100 feet high, 20 yards in 

 diameter at the base and cylindrico-conical in shape. It is merely 

 a limestone shell, the central portion being absent. The internal 

 contour is approximately a reflex of the exterior. Tiny entrances 

 occur in the undercut portions, through which the sea has free 



* A. Agassiz, Bull. Mus. Comp. Zoology, Harvard Coll. Vol. xxxiii. p. 91. 



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