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JOURNAL, R.A.S. (CEYLON). [VOL. XVI. 



which becomes gelatinous and calcines in a series of con- 

 centric layers, while at its centre may be found a cavity 

 holding organic matter, the remains of the parasites which 

 gave it birth.* 



" Pearl," says Saville-Kent, " is, unfortunately, one of the 

 substances impermeable to the recently discovered Rontgen 

 rays ; otherwise the solution of this mystery .... might be 

 easily achieved. May be, however, in the near future a new 

 XX, XXX, or other occult luminant will be evolved which 

 shall possess the property of laying bare and naked the 

 nuclei of pearls."! 



The Pearl Fisheries of Australia, 

 The pearl fisheries of Australia, which have of late years 

 developed considerable proportions, are conducted in the 

 Torres Straits, on the coast of Queensland, and on* the 

 northern coast of Western Australia. Here the large pearl 

 oyster M. mar'garitifera is fished, primarily for the sake of 

 its shell, which furnishes the mother-of-pearl of commerce. 

 Pearls themselves, when discovered, are regarded as more or 

 less of a chance product, and are frequently appropriated by 

 the hired diver and boats' crew — and this may be said to be 

 commonly the custom in all the pearl fisheries of the South 

 Seas. The total value of the pearl-shell fishery of Queens- 

 land alone amounted in 1898 to £109,401 sterling. 



On the northern shores of Australia, in addition to the 

 mother-of-pearl shell (from which almost all Southern pearls 

 are derived), there occur two other species, viz., M. imbri- 

 cata, Rve., and M. fucata, Gould, which produce pearls. 

 The latter is identical with the pearl oyster of the Gulf of 

 Mannar, but is, curiously enough, regarded with disfavour 

 in the Australian region, where it is known as the " bastard " 

 shell, — probably because its shell is of little value as mother- 

 of-pearl, and also, perhaps, because it does not produce fine 

 " Oriental " pearls in the Southern Seas. 



* "Comptes Rendus," cxxviii., 1899, p. 1589-91. 

 t " The Naturalist in Australia," p. 201. 



