BOTANY OF THE I.ACCADIVE><. 275 



Cherbaniani^ a mere pile of coral blocks,* but exhibits the structure 

 characteristic of the larger formed-islands of the group ; that 

 is to say^ it consists of a soil of coral-sand mixed with a 

 greater or less amount of humus derived from decaying vegetation, 

 this soil overlying a friable calcareous rock with a coarse oolitic 

 structure, one foot to eighteen inches thick, beneath which is found 

 a loose wet sand from whence, if the crust be broken through, and 

 a few spadefuls of it be removed, water percolates and accumulates 

 in the hollow so formed. f In Bitra, however, though the overlying 

 soil is said to be excellent and the coco-nut grows luxuriantly, it is 

 impossible for the people to occupy the island permanently because 

 the water which accumulates in the wells made by sinking short 

 shafts through this coral crust, in place of being fresh and drinkable, 

 as in the inhabited islands, is so salt that the fishermen who visit the 

 place, when thej^ run short of water, dig a hole in the sand near the 

 sea and drink the brackish percolations thus obtained in preference 

 to the well-water.+ The island is sacred to a P/r whose tomb, 

 Mr. Robinson was told, has about 200 coco-nut trees planted round 

 it as votive offerings to his name. Mr. Hume speaks of the coco-nut 

 trees but does not mention the tomb. It stands. Dr. Alcock informs 

 the writer, near the north end of the island in the middle of the 

 Coco-nut grove, surrounded also by patches of one of the Ti(l>ii 

 plants. An indication that the island is often visited is the presence 

 in the Investigator collection of specimens of Bicuiiis communis 

 which is frequent as a weed. Besides the Castor-Oil, the Tulsi, and 

 the Coco-nut, the collections of Mr. Hume and Dr. Alcock contain 

 16 species, all but thi^ee of which are undoubtedly plants of the 

 littoral, sea-introduced class. It is important to note that the 

 Coco-nut does not occur in a fringe round the coast as would probably 

 be the case were that species here introduced by the sea ; besides 

 their being confined to the middle of the island we have the express 

 statement of the islanders to Mr. Robinson that the trees were 

 deliberately planted during their fishing and egg-collecting visits. 



* Hume, "Stray Feathers," vol. iv., p. 431. 



t Eobinson, "Madras Journal of Lit. and Science," vol. xiv., p. 7; Alcock 

 Hoskyn, " Marine Survey Report," 1889-90, p. 12. 

 X Robinaou, " Madr. Jouru." vol. .kIv., p. 27. 



