HISTORY OF THE PRINCIPAL PEARL RANKS. 



15 



of spat either disappear (as in the case of those marked 1, 4, and 6) or expand and 

 join (as in the case of 2, 3, and 5) to form eventually a continuous Led ; (2) that if 

 all goes well, as the oysters grow older they increase, for a time, their area of 

 distribution, e.g., we have the two beds of 1871 joining and expanding to form the 

 much larger area of 1872, which again increases somewhat in 1873 ; (3) after a time, 

 however, the oysters, now over 3 years old, begin to die off, and shrinkage of the bed 



c<0 



SkaA - iayo 



lyr. IP7I 



iyr. ii7<. 



3yr i? 



Fig. 4. History of one generation of pearl oysters on the West Cheval Paar from the fall of " spat " 



in 1870 to the fishery of 1874. 



takes place, so that the area fished in 1874 is considerably smaller than that occupied 

 in 1873 or in 1872, and is no larger than the two beds of young oysters present in 

 1871. In accounting for such changes in the position and the extent of the bed, it is 

 necessary to bear in mind (l) the very considerable powers of locomotion, especially 

 of the young oyster, and (2) the damage done to a bed by both animate and inanimate 

 foes. These have already been discussed in Part I. of this Report. 



In order to illustrate more fully the irregular distribution of the oysters on the 

 ground, the large areas that may remain unoccupied on a paar and the changes that 

 take place during the development of a deposit of spat into a fishable bed of oysters, 

 we shall now give a series of diagrams compiled from the MS. notes and plans of the 

 periodic inspections deposited in the Master Attendant's Office at Colombo. They 

 deal with the last 20 years, from March, 1884, and show (tigs. 5 and 6) an extensive 

 bed of young oysters which yielded fisheries in 1887 and 1888, various scattered 

 deposits of young oysters (tigs. 7 and 8) which apparently came to nothing, and 

 finally (figs. 9 to 14) the detailed history of the extensive bed of young oysters which 

 was first seen on the Western and Southern Cheval in March, 1900, afterwards spread 

 on to the East, and eventually gave rise to the two recent very important fisheries, 

 on the East Cheval in 1903 and on the West in 1904. Although these last oysters 



