Feis., 1904.] 



KXcn\LEDGl-: c^ SCIl'XTll'lC xi:\\s. 



problems that were involved, and accordingly com- 

 missioned Professor \\'. A. Herdman, F.R.S., of the 

 Natural History Department of the rni\ersity of 

 Liverpool, to proceed to Ceylon, in company with a 

 qualified scientific assistant, to commence a survey and 

 carry out a series of investigations and experiments. 

 The steamship Liuiy Hiizvloik was placed by the Ceylon 

 authorities at Professor Herdman's disposal for the work 

 of examining the biological surroundings of the pearl 

 oyster banks, and during two successive cruises of three 

 or four weeks e.ach he inspected out at sea all the prin- 

 cipal banks, established lines of dredging and trawling, 

 and made observations across, around, and between the 

 banks in order to ascertain the conditions that satisfy an 

 oyster " paar," the term applied to the varied rocky 

 strata (as opposed to shifting sandy layers) beneath the 

 water which constitute the habitat of the animal. In all 



iNative Divers employed by l*rof. Herdman. 



these operations the Professor found an able coad- 

 jutor in Mr, James Hornell, his assistant, who, it 

 may be added, is still in Ceylon furthering the 

 enquiry. Enough, however, has already been 

 accomplished to permit the issueof a detailed report 

 embracing a description of the banks, and a record 

 of the studies that were made on the life-history 

 of the pearl oyster itself. The accompanying illus- 

 trations we are privileged to reproduce from this 

 Report, 



Much virtue often attaches to a name, but in the 

 case of the so-called pearl oyster we have to disabuse 

 our mind of any lingering belief that it is a true 

 oyster, since, as a matter of fact, the animal belongs 

 to the family Aviculidse, and is therefore more 

 nearly related to the Mussels [Mytiliis) than to the 

 Oysters {Ostraa) of British seas. One character 

 in particular marks it ofT from Ostraa, namely, 

 the ownership of a " byssus," or bundle of tough 

 threads, by means of which it can tag itself on 

 to rocks or other adjacent objects, as do its con- 



geners, the Mussels, The species has favoured Ceylon 

 waters, or, more strictly, tlie shores of the Culf of Manaar 

 on the north-west, in countless generations from icnioti' 

 antiquity, hence, long prior to ICuropean rule ; while the 

 praises of the "orient" pearl ha\-e been unilnrmiy e\- 



A Bunch of Oysters from the sea hotloni. Four generations are seen. 



I he iarpest is xi years old, anJ the smallest, attached to the 



lart^e shell, is about a month old. 



tolled in many a classical allusion. .\li over the district 

 the pearl oyster of the banks is the same animal, a 

 decision that was quickly arrived at by Professor 

 Herdni:in ; lurthermDre, the method of fishery now pur- 

 sued, even to the manning of the divers' boats and the 

 custom of the cessation of diving at noon, is a continua- 

 tion of ancient practice. 



Of the causes which lead up to the disappearance of 

 the oyster population — sometimes in hundreds of thou- 

 sands — and the de\-astation of the banks, the Commis- 

 sioner has much to say that is of interest. Influences 

 such as oceanic currents, monsoon storms, and shifting 

 sands have each their play ; added to wliich, in common 

 with other classes of marine denizens, the pearl oyster 

 has its enemies. Boring sponges may destroy the shell, 

 and boring molluscs suck out the animal. Then there 

 are the star-fishes and carnivorous fishes to reckon with. 

 But, as Professor PIcrdman remarks, compensation arises 



One (tf the enemies 



Half natural si/e. 



