THE ECONOMIC USES OF SHELLS. 465 



"In view of the immense importance and value of these fisheries, an effort 

 was recently made by the Colonial officers of the British Government to inves- 

 tigate the causes of these barren years, and also to find a remedy for them ; 

 and Prof. W. A. Herdman was asked to examine the records on this subject 

 and to repoit on them. Following this report came a request by the Govern- 

 ment that he should make a personal investigation of the pearl banks, and with 

 Mr. Hornell, an assistant, he went to Ceylon and set about the work. 



" The first step in the investigation was to make a complete survey of the 

 whole sea bottom of the area of the pearl fisheries. This was done partly by 

 sounding and dredging, and partly by the aid of divers, Mr. Hornell himself 

 doing some investigation in a diving suit. Thus was gained much information 

 as to the nature of the ground best suited to the growth of the pearl-oyster and 

 the dangers to which the animal is exposed. It has many active enemies* such 

 as sponges and mollucs and star-fishes, which bore through the shell, fishes and 

 internal parasites. Yet, on the whole, the destruction caused by these agents 

 is slight, compared with that caused by shifting sands, which overwhelm whole 

 beds of oysters, burying and killing them. A bed of oysters, examined in 

 March, which extended over an area of sixteen square miles, was covered by 

 a vast multitude of young oysters ' so closely packed that the bank must have 

 held not less than one hundred thousand million. ' In November of the same 

 year the spot was revisited and the oysters had disappeared, having been buried 

 in the sand or swept down a steep slope outside the bed. 



" Overcrowding is another fruitful cause of destruction which Professor 

 Herdman suggests may be avoided by transplanting. That the star-fishes 

 cause much damage is shown by an example given of a crop of oysters estima- 

 ted in March 1902, as 5f millions, which had nearly disappeared by March 

 1903, from this cause." 



The other great pearl producing fisheries of the world are in the Persian 

 Gulf, of which the Island of Bahrein is the centre, and on the N. and N.-W. 

 Coasts of Australia, the pearls being found in varieties of the same species of 

 shell as in Ceylon waters. The Persian Gulf shells are known to the trade as 

 " Lingah " shells from the principal port from which they are shipped, as these 

 shells are sent to market for their mother-of-pearl value. The general method 

 of procedure in the fishing is the same as in Ceylon. 



On the west coast of India there are pearl fisheries at various places, but 

 the gems are of comparatively small value. The most important of these is off 

 the State of Nawanagar on the south side of the Gulf of Cutch, where the true 

 pearl oyster is found, although it is rare on the coast generally. In confirmation 

 of its scarcity, Mr. E. H. Aitken writes roe that it " is not supposed to be found 

 between the Persian Gulf and Ceylon, but I have a perfect specimen (very 

 young) from the Uatnagiri coast and two halves from Kanara. " 



Having heard of the Nawanagar fisheries, and finding references to them in 

 the '« Bombay Gazeteer" of 1884, (Kathiawar, VIII, pp. 93 and 561), I tried to 

 learn something more about them. Mr. Chester Kincaid has been good enough to 



