61 



local fishermen, in answer to independent inquiries by Mi*. 

 Bruce Foote and myself, to extend only as far as Pillay 

 Mudum, 7 miles south-east of the Vigai river, which, though 

 easily crossed on foot in the dry season, is .in high flood 

 during the monsoon, and, for about a fortnight in the year, 

 impassable even on a raft. 



Piled up over a limited area at the base of the fossil 

 reef were masses and fragments of pumice ^ encrusted with 

 Polyzoa, C/umue, tubes of tubicolous worms, BaJani, young 

 pearl oysters, &c., and dislodged in the first instance, "in all 

 probability, from the volcano of Krakatoa during the great 

 eruption of 1883, a curious result of which has been that, in 

 the district of Charingin, which was depopulated by the tidal 

 wave during the outburst, tigers have increased so enor- 

 mously in number that the Grovernment reward for killing 

 them has been fixed at 200 guilders each. 



Washed on shore by the waves, protecting the upper 

 surface of the dead corals, or brought up for me from the 

 sea bottom by my divers, were nodular calcareous Algce, 

 which, from microscopical examination, I find to be identical 

 with those which were dredged off the town of Negombo 

 in Ceylon by Captain Cawne Warren, and reported on by 

 Mr. H. J. Carter.'^ " The specimens," says that authority, 

 " consist of calcareous nodules of different sizes, which may 

 be said to originate, in the first instance, in the agglutination 

 of a little sea bottom by some organism into a transportable 

 mass which, increasing after the same manner as it is cur- 

 rented about, may finally attain almost unlimited dimen- 

 sions. They are, therefore, compounded of all sorts of 

 invertebrate animals, whose embryoes, swimming about in 

 every direction, find them, although still free and detached, 

 of sufiicient weight and solidity to offer a convenient position 

 for development, and hence the number of species in and 

 about them .... Perhaps no family of organisms 

 has entered into their composition or increased their solidity 

 more than calcareous Algas {Meloieme) which, in successively 

 laminated or nulliporoid growths, have rendered these 



1 " The fragments of pumice thrown up into the ocean during far dis- 

 tant sub-marine eruptions, or washed down from volcanic lands, are at all 

 times to be found floating about the surface of the sea, and there beiug cast 

 upon the newly formed islet produce by their disintegration the clayey 

 materials for the formation of a soil, the red earth of coral islands." 

 Murrav, Eoyal Institution, March 16, 1888. 



2 Ann. May. Nat. Hist., June 1880. 



