56 



The bottom 011 the rocky patches is the usual ealcrete, the remainder of the 

 ground fine sand with occasional chanks. 



The young oysters found in 1901 lay principally on the sandy stretches. 



4. Cruxian Group. 



Another group of small pars, three in number, lying west of the island of Vautivu 

 and about six miles from the mainland. The three constituent pars, Cruxian, Tundu 

 and Tantivur Arupagam are to the north- north-west of the TJti group in rather shallower 

 water, 6 to 6| fathoms. 



The bottom on the pars consists of level stretches of continuous rock, brownish 

 tinted ealcrete exactly similar to that on the Uti pars. 



The fauna differs considerably from that of the last-named banks. Sponges are 

 less extensive, Siphonoclialina communis being the most conspicuous and numerous. 



Among other animals noted were large Pinna sp. in abundance rooted in the 

 thin layer of sand covering the rock in many places, with Balanus and zoophytes 

 crowding the exposed surfaces of the Pinna; Eariice tubifex in quantity ; Heteroneid 

 form of Nereis sp. in the canal system of Suberites inconstans ; Botrylhides sp. ; 

 Turlinella rapa in the sand on the western side. 



The large fishery of 1861 was contributed to from these banks, which appear 

 more favourably situated than many others for receiving spat falls, some eight being 

 recorded since 1861. Unfortunately in only three instances, 1878, 1884, and 1902, 

 did the re-stocking take place on an extensive scale ; — even in 1902 the quantity of 1~ 

 to 2 years old then present was estimated at but 1,700,000, a number too small to 

 give good results two to three years after in view of the unpreventable wastage that 

 must be allowed for. 



In many respects the Cruxian group has points of resemblance with the North 

 and South Moderagam Pars on the Ceylon side, notably in the in-shore situation, the 

 comparative shallowness of the water and in the characteristic abundance and associa- 

 tion together of Pinna and Balanus. 



The ground referred to on the Ceylon side is much the more clean of the two, 

 both faunistically and physically ; the sand there is of the usual coarse grit and this, 

 by the attrition of its movement during disturbed weather conditions effectually 

 scours the bank, keeping down the growth of weed and other organisms unprotected 

 by a hard external protective casing. 



This mechanical cleansing of the bottom is nowhere well seen on the in-shore 

 Indian banks where the fineness and low specific gravity of the sand lacks not only 

 an adequate scouring force, but by reason of the presence in it of a certain amount of 

 mud exercises a retarding influence upon oysters when they are present — an influence 

 resulting in a stunting of the growth. 



The fact has long been noted * that the size of Ceylon oysters of a given age from 

 the Cheval par is markedly superior to that of those of the same age from the in-shore 

 Indian banks, the latter approximating more closely to those from the Muttuvaratu 

 Par, a bank with a bad reputation for the starved appearance characteristic of its 



oysters. 



5. Vaipar karai Group. 



The largest of these is the Vaipar Karai Par, a bank of some importance not 

 located upon the present inspection chart. Prom the observations made and the 

 information supplied by the par mandadai, it appears to lie north-west of the Devi 

 Far and about five miles due south of the village of Vaipar. The other banks in this 

 grouping are the Devi, Pernandu, Padutta Marikan and Padutta Marikan Tundu Pars, 

 varying in diameter from half to three quarters of a mile. Depth 6 to 6|- fathoms. 



The bottom is of the usual reddish-brown limestone common to the other 

 groups in this neighbourhood, interrupted and more or less overlaid by a fine muddy 

 sand, the larger particles consisting chiefly of comminuted shells. Numerous dead 



* Thonias^H. Sullivan, he. oit., page 14. 



